path msk - formatted

Question 1

1. 76.APRIL02 A 61-year-old women has a bone scan after surgical resection of a node-negative 4-millimetre medullary breast carcinoma. This shows long areas of increased activity in the right fibula, left 6th and 12” ribs and the left frontal bone. This distribution is most typical of which of the following; (N.B. All alternatives are true causes of increased activity on bone scan).
2. Paget’s Disease of Bone
3. Metastatic disease
4. Fibrous dysplasia
5. Insufficiency fractures
6. Langerhan’s Histiocytosis

Answer 1

1. 76.APRIL02 A 61-year-old women has a bone scan after surgical resection of a node-negative 4-millimetre medullary breast carcinoma. This shows long areas of increased activity in the right fibula, left 6th and 12” ribs and the left frontal bone. This distribution is most typical of which of the following; (N.B. All alternatives are true causes of increased activity on bone scan).

ANSWER: 1. Paget’s Disease of Bone (ribs low down on list – most common pelvis,femur,skull and tibia. Mark and Eric agree but not specifically seen)

**LJS - not sure about this. Fibula is least common bone involved in Pagets, and ribs also uncommon. Seems unlikely they want you to pick Pagets by distribution and then list 2 uncommon locations. I would choose fibrous dysplasia or mets (though long lesions not typical). Can have polyostotic FD without it being syndromic (which is ass/w lesions in half body)

1. Paget’s Disease of Bone (ribs low down on list – most common pelvis,femur,skull and tibia. Mark and Eric agree but not specifically seen)
2. Metastatic disease
3. Fibrous dysplasia (unilateral)
4. Insufficiency fractures (skull)
5. Langerhan’s Histiocytosis (top 3 locations = skull,ribs and femora– long segments unusual)

Medullary Carcinoma
• Higher incidence in women carrying BRCA1 gene (13%)
• Usually 2 – 3 cm, but may be large fleshy tumours up to 5cm
• The prognosis is slightly better than that of other types ? all those lymphocytes fighting the cancer, or that this tumor is a distinct disease? Maybe both
• 5mm node negative with mets??? Give me a break, cant be true

Pagets
• Polyostotic (85%)
• pelvis (75%) > femur > skull > tibia > vertebra > clavicle > humerus > ribs

Polyostotic without Endocrine Dysfunction
• lesions may be confined to a single limb or single side of skeleton Langerhan’s Histiocytosis
• Any bone in skeletal system maybe involved
• most commonly skull (diploic space of parietal bone) (note epidermoid has sclerotic rim), ribs and femora

Question 2

2. 77.APRIL02 As a radiologist in a trial of non-accidental injury you are questioned about Vitamin C deficiency. Which of the following statements about scurvy is most correct?
3. There is a insufficient, osteoid matrix formation with slowing of cartilage resorbtion
4. There is a proportional reduction in both bone mineral and osteoid deposition
5. There is rapid cartilage growth leading to poor periosteal support
6. There is a primary disturbance in mineralisation of the bone matrix leading to cartilage overgrowth.
7. There is excessive but largely un-mineralised bone matrix simulating increased cartilage

Answer 2

2. 77.APRIL02 As a radiologist in a trial of non-accidental injury you are questioned about Vitamin C deficiency. Which of the following statements about scurvy is most correct?

ANSWER:1. There is a insufficient, osteoid matrix formation with slowing of cartilage resorption (there is insufficient production of osteoid matrix by osteoblasts, Resorption of the cartilaginous matrix then fails or slows; as a consequence, there is cartilaginous overgrowth)

1. There is a insufficient, osteoid matrix formation with slowing of cartilage resorption (there is insufficient production of osteoid matrix by osteoblasts, Resorption of the cartilaginous matrix then fails or slows; as a consequence, there is cartilaginous overgrowth)
2. There is a proportional reduction in both bone mineral and osteoid deposition (cartilage mineralisation not arrested)
3. There is rapid cartilage growth leading to poor periosteal support
4. There is a primary disturbance in mineralisation of the bone matrix leading to cartilage overgrowth.
5. There is excessive but largely un-mineralised bone matrix simulating increased cartilage (insufficient production of osteoid matrix)

• The primary disturbance is in the formation of osteoid matrix, rather than in mineralization or calcification, such as occurs in rickets.
• In scurvy, the palisade of cartilage cells is formed as usual and is provisionally calcified.
• However, there is insufficient production of osteoid matrix by osteoblasts.
• Resorption of the cartilaginous matrix then fails or slows; as a consequence, there is cartilaginous overgrowth, with long spicules and plates projecting into the metaphyseal region of the marrow cavity, and sometimes widening of the epiphysis

Question 3

3. 78.APRIL02 Concerning the early stages of osteoarthrosis which of the following statements is most correct?
4. The concentration of proteoglycans increases
5. Matrix water content decreases
6. Chondrocytes proliferate forming clones
7. Cartilage and subchondral bone fragments are present in the joint in large quantities
8. Bony eburnation is observed

Answer 3

3. 78.APRIL02 Concerning the early stages of osteoarthrosis which of the following statements is most correct?

ANSWER:3. Chondrocytes proliferate forming clones

1. The concentration of proteoglycans increases (decreases)
2. Matrix water content decreases (increases)
3. Chondrocytes proliferate forming clones
4. Cartilage and subchondral bone fragments are present in the joint in large quantities (intermediate stages)
5. Bony eburnation is observed (intermediate stages)

Early
• Chondrocyte proliferation
• increased matrix water
• decreased proteoglycans in cartilage matrix
• Fibrillation of cartilage + loss of superficial cartilage layers
• Cartilage surface granular & soft

Intermediate
• Nonspecific synovitis without pannus
• Eventually sloughing of full-thickness portions of cartilage with exposure of subchondral bone
• Friction results in bone eburnation
• Subchondral bone plate thickens & underlying cancellous bone becomes sclerotic
• Small fractures occur through subchondral bone plate
• Fragments of bone & cartilage form loose bodies within joint (loose bodies,joint mice)

Later
• Fractures through cartilage allow synovial fluid to be forced into subchondral regions forming fibrous walled subchondral cysts
• Cysts may also reflect rarefaction due to osteoclastic activity &/or osteocyte death
• Osteophytes develop at articular surface margins
o capped by fibrocartilage & hyaline cartilage that gradually ossifies
• Synovium becomes congested + fibrotic

Question 4

4. 79.APRIL02 Concerning rheumatoid nodules which of the following statements is most correct?
5. They typically occur in regions of skin subjected to pressure
6. They are usually manifest in patients with relatively mild disease
7. They only involve cutaneous structures
8. They occur in over 50% of patients
9. They are typically exquisitely tender

Answer 4

4. 79.APRIL02 Concerning rheumatoid nodules which of the following statements is most correct?

ANSWER:1. They typically occur in regions of skin subjected to pressure (rise in regions of the skin that are subjected to pressure, including the ulnar aspect of the forearm, elbows, occiput, and lumbosacral area)

1. They typically occur in regions of skin subjected to pressure (rise in regions of the skin that are subjected to pressure, including the ulnar aspect of the forearm, elbows, occiput, and lumbosacral area)
2. They are usually manifest in patients with relatively mild disease (severe disease)
3. They only involve cutaneous structures (lungs, spleen, pericardium, myocardium, heart valves, aorta, and other viscera)
4. They occur in over 50% of patients (25%)
5. They are typically exquisitely tender

• Rheumatoid nodules
o are the most common cutaneous lesion.
o They occur in approximately 25% of patients, usually those with severe disease, and arise in regions of the skin that are subjected to pressure, including the ulnar aspect of the forearm, elbows, occiput, and lumbosacral area.
o Less commonly, they form in the lungs, spleen, pericardium, myocardium, heart valves, aorta, and other viscera.
o Rheumatoid nodules are firm, nontender, and round to oval and in the skin arise in the subcutaneous tissue.
o Microscopically, they have a central zone of fibrinoid necrosis surrounded by a prominent rim of epithelioid histiocytes and numerous lymphocytes and plasma cells

Question 5

5. 80.APRIL02 Which of the following statements concerning Paget’s disease of bone lS LEAST correct?
6. There is an initial osteolytic phase
7. Current evidence suggests it is due to a slow virus infection of bone
8. Involvement of the ribs, fibula or small bones or the hands or feet is unusual
9. Recognised complications include malignant fibrous histiocytoma and chondrosarcoma
10. Whist there is a proliferation of osteoclasts, osteoblasts and bone resulting in cortical thickening, the overall lamellar pattern remains ordered in the absence of malignancy.

Answer 5

5. 80.APRIL02 Which of the following statements concerning Paget’s disease of bone lS LEAST correct?

ANSWER:5. Whist there is a proliferation of osteoclasts, osteoblasts and bone resulting in cortical thickening, the overall lamellar pattern remains ordered in the absence of malignancy. (The newly formed bone is disordered and architecturally unsound)

1. There is an initial osteolytic phase (initially active/osteolytic stage)
2. Current evidence suggests it is due to a slow virus infection of bone (Slow virus infection of osteoblasts / osteoclasts by paramyxovirus → promotes secretion of IL-6 from infected cells → potent stimulator of osteoclast activity & bone resorption)
3. Involvement of the ribs, fibula or small bones or the hands or feet is unusual (pelvis (75%) > femur > skull > tibia > vertebra > clavicle > humerus > ribs)
4. Recognised complications include malignant fibrous histiocytoma and chondrosarcoma (malignant fibrous histiocytoma 25% and chondrosarcoma 5%)
5. Whist there is a proliferation of osteoclasts, osteoblasts and bone resulting in cortical thickening, the overall lamellar pattern remains ordered in the absence of malignancy. (The newly formed bone is disordered and architecturally unsound)

•	Sarcomatous Change in ~ 1% → lytic lesion often with cortical breakthrough 
o	50% osteosarcoma 
o	25% malignant fibrous histiocytoma 
o	15% remainder fibrosarcoma 
o	5% chondrosarcoma 
o	5% GCT 
o	→ suggested clinically by 
(1) change in type & severity of bone pain (2) enlarging mass (3) pathological fracture  

Question 6

6. 81.APRIL02 Concerning ankylosing spondylitis which of the following statements is most correct?
7. It is only observed in individuals who are HLA-B27 positive
8. It is not associated with synovitis
9. It is the only condition in which syndesmophytes are observe
10. It is associated with rheumatoid factor positivity in over 50% of cases
11. It involves peripheral joints (e.g. knees, hips shoulders) in over 20% of patients.

Answer 6

6. 81.APRIL02 Concerning ankylosing spondylitis which of the following statements is most correct?

ANSWER:5. It involves peripheral joints (e.g. knees, hips shoulders) in over 20% of patients. (Peripheral large joints - hips, shoulders, knees are involved in up to 1/3)

1. It is only observed in individuals who are HLA-B27 positive (90-95% positive)
2. It is not associated with synovitis (Chronic synovitis)
3. It is the only condition in which syndesmophytes are observe (Rieters)
4. It is associated with rheumatoid factor positivity in over 50% of cases
5. It involves peripheral joints (e.g. knees, hips shoulders) in over 20% of patients. (Peripheral large joints - hips, shoulders, knees are involved in up to 1/3)

Question 7

7. 82.APRIL02 Concerning gouty tophi which of the following statements is most correct?
8. They are pathognomonic for gout
9. They are due to aggregations of metabisodium urate crystals
10. They are most frequently present in relation to the olecranon bursa
11. They comprise monosodium urate crystals surrounded by neutrophils and epithelioid histiocytes
12. They are not observed in relation to the kidney

Answer 7

7. 82.APRIL02 Concerning gouty tophi which of the following statements is most correct?

ANSWER:1. They are pathognomonic for gout

1. They are pathognomonic for gout
2. They are due to aggregations of metabisodium urate crystals
3. They are most frequently present in relation to the olecranon bursa
4. They comprise monosodium urate crystals surrounded by neutrophils and epithelioid histiocytes
5. They are not observed in relation to the kidney

• Tophi
o are the pathognomonic hallmark of gout.
o They are formed by large aggregations of urate crystals surrounded by an intense inflammatory reaction of macrophages, lymphocytes, and large foreign body giant cells, which may have completely or partially engulfed masses of crystals
o Tophi may appear in the articular cartilage of joints and in the periarticular ligaments, tendons, and soft tissues, including the olecranon and patellar bursae, Achilles tendons, and ear lobes.
o Less frequently, they may appear in the kidneys, nasal cartilages, skin of the fingertips, palms, or soles as well as elsewhere.
o Superficial tophi can lead to large ulcerations of the overlying skin.

• Gouty nephropathy
o refers to the renal disorder associated with the deposition of monosodium urate crystals in the renal medullary interstitium, sometimes forming tophi, intratubular precipitations, or free uric acid crystals, and the production of uric acid renal stones.
o Secondary complications, such as pyelonephritis, may ensue, particularly when the urates induce some urinary obstruction.

• On average, it takes about 12 years between the initial acute attack and the development of chronic tophaceous arthritis

Question 8

8. 83.APRIL02 Seronegative spondyloarthropathies DO NOT include
9. Ankylosing spondyiitis
10. Reiter syndrome
11. Enteropathic arthritis
12. Psoriatic arthritis
13. Calcium pyrophosphate deposition disease

Answer 8

5. Calcium pyrophosphate deposition disease

Question 9

9. 21.03.16 Ewings sarcoma versus osteomyelitis, LEAST LIKELY if ? Rob p21
10. Fever
11. Afro-American

Answer 9

9. 21.03.16 Ewings sarcoma versus osteomyelitis, LEAST LIKELY if ? Rob p21

ANSWER:2. Afro-American (Ewings- Caucasions 96%)

1. Fever (Ewings- Fever, raised ESR, anaemia, leukocytosis suggesting infection)
2. Afro-American (Ewings- Caucasions 96%)

Ewings Sarcoma vs Osteomyelitis :
• Duration of symptoms shorter (<2 weeks)
• May look identical
• M:F = 2:1
• Caucasians in 96%, blacks are rarely afflicted
• Of all bone sarcomas, Ewing sarcoma has the youngest average age at presentation as most patients are 10 to 15 years old
• approximately 80% are younger than 20 years.
• In approximately 85% of Ewing sarcomas and PNETs, there is a t(11;22)(q24;q12) translocation
• Location: femur (25%), pelvis-ilium (14%), tibia (11%), humerus (10%), fibula (8%), ribs (6%)
• long bones in 60%: flat bones in 40%
• The treatment of Ewing sarcoma includes chemotherapy and surgery with or without radiation. The advent of effective chemotherapy has dramatically improved the prognosis from a dismal 5% to 15% to a 75% 5-year survival; at least 50% are long-term cures.

Question 10

10. 21.03.81 Osteoporosis which is MOST TRUE ? Rob p757
11. Increase bone density
12. Senile Osteoporosis increase osteoblast activity
13. Treatment with disphosphonates to stimulate osteoblasts
14. Delayed fracture healing with callous formation
15. Decrease serum calcium and phosphate

Answer 10

4. Delayed fracture healing with callous formation (Delayed fracture healing with poor callus formation )
5. 21.03.81 Osteoporosis which is MOST TRUE ? Rob p757
6. Increase bone density (postmenopausal - >2.5 SD below normal / age related – low normal)
7. Senile Osteoporosis increase osteoblast activity (low turnover form of osteoporosis)
8. Treatment with disphosphonates to stimulate osteoblasts (inhibit osteoclastic bone resorption; parathyroid hormone stimulates osteoblastic activity)
9. Delayed fracture healing with callous formation (Delayed fracture healing with poor callus formation )
10. Decrease serum calcium and phosphate (serum calcium and serum phosphorus normal)

• Osteoblasts from elderly individuals have reduced reproductive and biosynthetic potential when compared with osteoblasts from younger individuals
• Probably bad recall as none appear right
• Diphosphonates inhibit osteoclastic action ,not incr. osteoblastic action
• If ‘d’ said delayed fracture healing and poor callus formation then it would be correct

POSTMENOPAUSAL OSTEOPEROSIS ( TYPE 1)

• age : 55-76
• sex : female 6 :1
• path: increased osteoclast activity
• trabecular bone loss
• rapid high turn over bone loss- > 2.5SD below normal

(DEXA)AGE-RELATED SENILE (TYPE 2)

• age: > 70f, > 80 M
• sex: female 2:1
• path : decreased osteoblast activity
• cortical and trabecular bone loss
• slow bone loss, low bone turnover
• low normal bone density (age and sex adjusted)

Question 11

11. 21.03.83 Chondrosarcomas ? Rob p766
12. chondroblastoma may give rise to chondrosarcoma
13. grade I – III < 40% 5ys
14. chondroblastic osteosarcoma is part of chondrosarcoma classification
15. Occur 15-40 years

Answer 11

11. 21.03.83 Chondrosarcomas ? Rob p766

ANSWER:1. chondroblastoma may give rise to chondrosarcoma (Although a significant number of conventional chondrosarcomas arise in association with a preexisting enchondroma, few develop within an osteochondroma, chondroblastoma, or fibrous dysplasia or in the setting of Paget disease)

**LJS - caution - more recent Robbins lists only enchondroma and osteochondroma as lesions in which secondary chondrosarcoma arises. Other sources (RP, stat dx) say can get rare malignant chondroblastoma, but doesn’t call them chrondrosarcoma
Other options incorrect, so presumably right answer at the time

1. chondroblastoma may give rise to chondrosarcoma (Although a significant number of conventional chondrosarcomas arise in association with a preexisting enchondroma, few develop within an osteochondroma, chondroblastoma, or fibrous dysplasia or in the setting of Paget disease)
2. grade I – III < 40% 5ys: FALSE (grade 1 – 90% , grade 2 80% , grade 3 40%)
3. chondroblastic osteosarcoma is part of chondrosarcoma classification: FALSE (Osteosarcoma)
4. Occur 15-40 years; FALSE (peak 40 -60 years)

Occurrence

1. Primary (de novo) - 75%
2. Secondary (complication of preexisting skeletal abnormality) – 25%
3. Enchondroma
4. Chondroblastoma
5. Osteochondroma
6. Fibrous dysplasia
7. Paget’s disease

5 year survival:
grade 1 = 90%
grade 2 = 80%
grade 3 = 40%

Morphological variants

1. Conventional intramedullary
2. Juxtacortical / periosteal - ?Arise in pre-existing cortical lesion e.g. osteochondroma, chondroma
3. Clear cell - Tend to occur in younger patients + in epiphyses following closure of growth plate
4. Dedifferentiated
5. Mesenchymal

Question 12

12. 21.02.26 Girl presents with precocious puberty and expansile lesions in pelvis and proximal femur. Which other bones are likely to be involved?
13. Ribs, skull, jaw
14. Tibia, skull, spine
15. Spine, wrist
16. Neck,chest,back,shoulder and pelvic region

Answer 12

12. 21.02.26 Girl presents with precocious puberty and expansile lesions in pelvis and proximal femur. Which other bones are likely to be involved? (McCune-Albright Syndrome) ? Big Rob p 1243 Dan p76

ANSWER:2. Tibia, skull, spine

**SCS:Disagree. I favour A.
Robbins: “polyostotic FD manifests at a slightly earlier age. Bones affected in descending order of frequency; femur, CALVARIUM, tibia, RIBS, fibula, radius, ulna, MANDIBLE and THEN vertebrae,” 9thED, pg 1206. Very niggly.

Also Radiopaedia; spine lower down on list of polystotic involvement (lumbar 14% cervical 7%).

1. Ribs, skull, jaw
2. Tibia, skull, spine
3. Spine, wrist
4. Neck,chest,back,shoulder and pelvic region

McCune-Albright Syndrome - polyostotic fibrous dysplasia
• skull, spine, and long bones
• Involvement of the skull can be particularly problematic, with lesions of the orbit resulting in visual loss and/or proptosis, and lesions of the ear resulting in deafness and vertigo.
• As with the cutaneous lesions, the bony lesions are not uniformly distributed and tend to be unilateral.

Question 13

13. 21.02.37 Osteosarcoma definition ? Rob p766

Answer 13

1. Malignant tumour with the ability to produce osteiod directly from neoplastic cells

Question 14

15. 21.02.80 Histology of non-ossifying fibroma
16. Consists of unossified cartilage
17. Consists of acellular fibrous material
18. Spindle cells in fibrous tissue in storifirm pin wheel pattern with foamy histicytes
19. Cystic spaces lined by fibrous septae filled with blood without endothelium lining

Answer 14

3. Spindle cells in fibrous tissue in storiform pin wheel pattern with foamy histicytes

• Spindle cell fibrous tissue arranged in interlacing storiform (pinwheel) pattern
• Variable number of benign fibroblasts, scattered osteoclast-type giant cells, lipid-bearing foamy histiocytes (xanthoma cells), and haemosiderin
o Foam cells more common in older lesions
o Hemosiderin pigment in stromal cells

Question 15

16. Sep03.16 Paget’s disease characteristics:
17. unusually large multinucleated osteoclasts in the lytic phase
18. characteristic woven bone
19. caused by a slow virus – rotavirus

Answer 15

Answer: unusually large multinucleated osteoclasts in the lytic phase (Aggressive bone resorption by giant, multinucleated osteoclasts)

ROBBINS
- In the initial lytic phase, there are waves of osteoclastic activity and numerous resorption pits.
- the osteoclasts are abnormally large, with >10 nuclei present

• in the mixed phase, osteoclasts persist, but now many of the bone surfaces are lined by osteoblasts.
• the newly formed bone may be woven of lamellar, but eventually all it remodeled to lamellar bone.
• Hallmark of Paget’s Disease is a mosaic pattern of lamellar bone, seen in the sclerotic phase.
• This jigsaw puzzle-like appearance is produced by unusually prominent cement lines, which join haphazardly oriented units of lamellar bone.
• Cell cultures studies suggest that chronic infection of osteoclast precursors by measles, paramyxovirus or other RNA viruses may play a role in the disease.

Question 16

17. Sep03.27 Chondrosarcoma – differentiating from other chondroid tumours
18. Peripheral skeleton
19. Intramedullary chondroid matrix surrounding trabeculae
20. Cellular atypia
21. Chicken wire appearance

Answer 16

17. Sep03.27 Chondrosarcoma – differentiating from other chondroid tumours

ANSWER:2. Intramedullary chondroid matrix surrounding trabeculae

1. Peripheral skeleton: FALSE (Commonly arise in central portions of skeleton → pelvis, shoulder, ribs, proximal femur, proximal humerus)
2. Intramedullary chondroid matrix surrounding trabeculae: TRUE
3. Cellular atypia; FALSE
4. Chicken wire appearance: FALSE (chondroblastoma - sheets of small, round chondroblasts surrounded by primitive chondroid matrix in a lace-like pattern which, when calcified, gives a chicken-wire pattern)

• Difficult to distinguish low grade chondrosarcomas from enchondromas
o Helpful diagnostic features of chondrosarcoma:
1. Plump multinucleated cartilage cells
2. Permeation through cancellous bone, replacing marrow and encasing trabeculae
3. Endosteal scalloping &/or focal cortical destruction
4. Cortical thickening

• To differentiate chondrosarcomas with foci of ossification from osteogenic sarcoma with chondroid differentiation:
o in chondrosarcomas, bone formation occurs within cartilage
o in osteosarcomas bone arises directly from anaplastic osteoblastic cells

Question 17

18. Sep03.67 Synovial sarcoma
19. most common in tendon sheaths of fingers/toes
20. Metastasises to regional LN’s, lung and bones

Answer 17

18. Sep03.67 Synovial sarcoma

ANSWER:2. Metastasises to regional LN’s, lung and bones

1. most common in tendon sheaths of fingers/toes (knee most common), hip, ankle, elbow, wrist, hands, feet )
2. Metastasises to regional LN’s, lung and bones

Synovial sarcoma
• <10% intra articular
• 10% of soft tissue sarcomas (4th) . -> PUS > liposarcoma > something > synovial sarcoma
• 20’s-40’s
• In the vicinity of the large joints of the extremities.
• 60-70% around lower extremities, especially knee
• The histological hallmark of synovial sarcomas is the biphasic morphology of the tumour cells (i.e. epithelial like and spindle cells)
• 5 year survival 25-60%
• Mets to regional LN’s lung and skeleton r

Question 18

19. Liposarcoma. Most correct statement
20. occurs in retroperitoneum and proximal limbs
21. 2-8 years of age
22. 50-80 years of age

Answer 18

19. Sep03.XX. Liposarcoma. Most correct statement

ANSWER:1. occurs in retroperitoneum and proximal limbs

1. occurs in retroperitoneum and proximal limbs
2. 2-8 years of age
3. 50-80 years of age

• Liposarcomas are one of the most common sarcomas of adulthood and appear in the forties to sixties; they are uncommon in children.
• They usually arise in the deep soft tissues of the proximal extremities and retroperitoneum and are notorious for developing into large tumors

Question 19

20. Sep03.87 Osteoblastoma vs Osteoma
21. no such thing as an osteoblastoma
22. spinal involvement

Answer 19

20. Sep03.87Osteoblastoma vs osteoid osteoma

ANSWER:2. spinal involvement (osteoblastoma involves the spine more frequently)

• Identical histological features
• differ in size, sites of origin, and symptoms

Osteoid Osteoma
• <2cm
• 75% < 25 yo
• 50% femur and tibia.
• Predilection for appendicular skeleton
• commonly in cortex, less frequently medulla
• painful. Relieved by aspirin

Osteoblastoma
• Involves spine more frequently
• Dull ache
• Not associated with marked bony reaction
• involves the spine more frequently and is usually larger than 2cm, and the pain does not respond to salicyclates

Question 20

21. PATH2004 The feature most diagnostic of gout is:
22. Acute pain 1st MTP joint
23. -ve birefringent crystal on aspirate
24. para articular erosions
25. hyperuricemia

Answer 20

-ve birefringent crystal

Question 21

22. PATH2004 Rh nodules – least likely site:
23. Pinna of ear
24. Ulnar surface forearm
25. Kidney
26. Spleen

Answer 21

22. PATH2004 Rh nodules – least likely site

ANSWER: kidney

1. Pinna of ear
2. External surface forearm
3. Kidney
4. Spleen

• Rheumatoid nodules are the most common cutaneous lesion. They occur in approximately 25% of patients, usually those with severe disease, and arise in regions of the skin that are subjected to pressure, including the ulnar aspect of the forearm, elbows, occiput, and lumbosacral area. Less commonly, they form in the lungs, spleen, pericardium, myocardium, heart valves, aorta, and other viscera.
• Microscopically, they have a central zone of fibrinoid necrosis surrounded by a prominent rim of epithelioid histiocytes and numerous lymphocytes and plasma cells

Question 22

23. PATH2004 CPPD, which is incorrect:
24. Hypo Mg
25. RA
26. OA
27. Hemochromatosis

Answer 22

23. PATH2004 CPPD, which is incorrect:

ANSWER: RA

1. Hypo Mg
2. RA
3. OA
4. Hemochromatosis

• Three main associated conditions (i.e. often present when CPPD present – do not cause CPPD):

1. Primary hyperparathyroidism
2. Haemochromatosis
3. Gout (40% with gout have CPPD)

•	Other associations: 
o	Prior joint damage i.e. OA 
o	Hypomagnesaemia
o	Hypothyroidism 
o	Ochronosis 

• Calcium pyrophosphate crystal deposition disease (CPPD), also known as pseudogout and chondrocalcinosis
• It usually occurs in individuals over 50 years of age and becomes more common with increasing age, rising to a prevalence of 30% to 60% in those 85 years or older.
• The sexes and races are equally affected.
• CPPD is divided into sporadic (idiopathic), hereditary, and secondary types.
• In the hereditary variant, the crystals develop relatively early in life and are associated with severe osteoarthritis. One family with this disorder showed linkage of the disease with chromosome 8q.
• The secondary form is associated with various disorders, including
o previous joint damage
o hyperparathyroidism
o hemochromatosis
o hypomagnesemia
o hypothyroidism
o ochronosis
o diabetes
o gout.
May mimic other disorders eg RA

Question 23

24. PATH2004 PVNS, which is incorrect:
25. Ankle commonest
26. not neoplastic
27. causes erosions

Answer 23

• LW: likely poor recall, or which is correct.
  1. Ankle commonest: FALSE - knee most common.
  2. not neoplastic: FALSE - genetic alterations within PVNS confirms neoplastic process.
  3. causes erosions: TRUE - usually pressure related erosions.

Previous answer:
1. knee is most common, not ankle
• knee commonest 80% followed in frequency by the hip, ankle, and calcaneocuboid joints
• They were previously considered reactive synovial proliferations (hence the designation synovitis); however, cytogenetic studies have demonstrated consistent chromosomal aberrations in these lesions indicating that they arise from a clonal proliferation of cells and are neoplastic

Question 24

25. PATH2004 Chondrocalcinosis is not found in:
26. Hemochromatosis
27. RA
28. Hypomagnesemia

Answer 24

not found in RA.

Question 25

1. Ewings sarcoma versus osteomyelitis, less likely Ewings if:

a. Fever
b. Afro-American
c. Involves ilium
d. Regional lymphadenopathy
e. Pathological fracture

Answer 25

answer: b. Afro-American T - 96% of Ewing’s sarcoma occurs in Caucasians
1. Ewings sarcoma versus osteomyelitis, less likely Ewings if: (GC)

a. Fever F - Ewing’s may present with fever, leukocystosis and anaemia
b. Afro-American T - 96% of Ewing’s sarcoma occurs in Caucasians
c. Involves ilium F - involves flat bones in 40% (predominant location in >20 yo)
d. Regional lymphadenopathy F - present in up to 30% of Ewing’s at time of diagnosis
e. Pathological fracture F - may complicate both Ewing’s and OM [Dahnert 6th, p75]

Question 26

2. Solitary plasmocytoma of bones of nasal cavity, which is true:

a. Usually surgically incurable
b. Most develop multiple myeloma
c. Extraosseous sites include the liver and spleen
d. Comprises part of the POEMS syndrome
e. Is not regarded a true monoclonal gammopathy

Answer 26

answer: most develop into multiple myeloma
* *LJS - 20% go on to develop MM

*LW:
UTD quotes A little more than half of patients with SPB will eventually develop overt MM.
Tx of choice is radiation.

2. Solitary plasmocytoma of bones of nasal cavity, which is true: (GC)
   a. Usually surgically incurable F - usually cured by surgical resection.
   b. Most develop multiple myeloma T

c. Extraosseous sites include the liver and spleen F - mainly upper respiratory tract (sinuses, nasopharynx, larynx).
* *LJS - GI tract 2nd most common site (stat dx). ?this more true than b?

d. Comprises part of the POEMS syndrome F - polyneuropathy, organomegaly, endocrine abnormalities, myeloma (sclerotic form), skin changes.
e. Is not regarded a true monoclonal gammopathy F - accounts for 3-5% of monoclonal gammopathy. [Robbins, Dahnert 6th p124]

WJI: this will come down to wording. While LW is correct most solitary bone plasmacytoma progress to MM, most solitary extramedullary plasmacytomas don’t. I doubt the stem said “bones of nasal cavity” as nasal cavity is classic (85%) for extramedullary rather than bony plasmacytoma. I think answer is c. As Liver and spleen are sites of extramedullary plasmacytoma. Presumably this is just asking about sites of extraosseous plasmacytoma in general because if you had it in your nose and spleen that would be 2 places so not solitary palsmacytoma anymore.

Question 27

3. Osteoporosis, which is most correct:

a. Decreased bone density
b. Senile osteoporosis, increased osteoclast activity
c. Treated with diphosphonate to stimulate osteoblasts
d. Delayed fracture healing with poor callus formation
e. Decreased serum calcium and phosphate

Answer 27

3. Osteoporosis, which is most correct: (GC) ANSWER: d. Delayed fracture healing with poor callus formation T
   a. Decreased bone density T - reduced bone mass of normal composition. But would be more specifically defined as a T-score of -2.5.
   b. Senile osteoporosis, increased osteoclast activity F - due to decrease in replicative activity of osteoprogenitor cells and synthetic activity of osteoblasts (low turnover form of osteoporosis). Postmenopausal type: decreased E2 levels result in an increased secretion of IL-1 by blood monocytes (IL-1 is a potent stimulator of osteoclast recruitment and activity) = high turnover form.
   c. Treated with diphosphonate to stimulate osteoblasts F - diphosphonates inhibit osteoclast activity, thus reduce bone resorption.
   d. Delayed fracture healing with poor callus formation T
   e. Decreased serum calcium and phosphate F - serum levels of calcium, phosphorus and ALP are notoriously insensitive. [Robbins, Dahnert 6th p3-4]

Question 28

Bowen’s disease, which is true:

a. SCC in situ
b. Multiple BCC
c. Multiple SCC
d. Precursor of melanoma

Answer 28

ANSWER: a. SCC in situ - variant of in situ ca of penis, occurs in older uncircumscribed males. Strongly assocd with HPV infection. Solitary plaque-like lesion on shaft.

4. Bowen’s disease, which is true: (GC)

a. SCC in situ - variant of in situ ca of penis, occurs in older uncircumscribed males. Strongly assocd with HPV infection. Solitary plaque-like lesion on shaft.
b. Multiple BCC F- assocd hereditary syndrome is Gorlin’s (AD; multiple BCCs and OKCs, palmoplantar pits, ectopic calcification, skeletal abnormalities).
c. Multiple SCC F
d. Precursor of melanoma F - precursors are dysplastic naevi, particularly if familial. [Robbins]

*Google search also came up with anal carcinoma -in-situ = Bowens disease

Question 29

5. Chondrosarcomas, which is true:

a. Arise in same area as enchondromas
b. Low-grade tumours have a 5 year survival rate of 70%
c. Chondroblastic osteosarcoma is a recognised type
d. Occur 15-40 year olds

Answer 29

Answer: A or B (see below) or incomplete stem

ROBBINS
- Conventional: >40 years old
- Clear cell/mesenchymal: teens/20s.
- M>F 2:1

• Chrondroscarcomas commonly arise in the axial skeleton, especially the pelvis, shoulder, and ribs
• Unlike enchondroma, the distal extremities are rarely involved.
• Only 15% of conventional chondrosarcomas are secondary, arising from a pre-existing enchondroma or osteochondroma
• Grade 1 chondrosarcoma 5-year survival of 80-90%
• Grade 3 chondrosarcoma 5-year survival of 43%

5. Chondrosarcomas, which is true: (GC)
   ANSWER: a. Arise in same area as enchondromas T - central metaphyseal lesion, may extend into diaphysis - low-grade CSA is radiographically & histologically indistinguishable from enchondroma.

a. Arise in same area as enchondromas T - central metaphyseal lesion, may extend into diaphysis - low-grade CSA is radiographically & histologically indistinguishable from enchondroma.
b. Low-grade tumours have a 5 year survival rate of 70% F - 90% 5YS for grade 1, 80% grd 2.
c. Chondroblastic osteosarcoma is a recognised type F - morphological variants inlcude: conventional intramedullary (most common), juxtacortical (periosteal), clear cell, dedifferentiated, mesenchymal.
d. Occur 15-40 year olds F - 40-70 yo. Younger age group if clear cell variant (20-30yo.), or mesenchymal variant (20-40yo.) [Adelaide path notes]

Changed b. from “have a good prognosis (5YS 70%)” - bit misleading.

Question 30

1. Sep03.04 SLE, which is false:

a. Type III hypersensitivity reactions account for most of the systemic lesions
b. The presence of antibodies to dsDNA is virtually diagnostic
c. Discoid rash and oral ulcers are diagnostic criteria
d. Lupus anticoagulant is a misnomer.
e. Inflammation of small arteries and veins is characteristic

Answer 30

1. Sep03.04 SLE, which is false: (GC)

ANSWER:. Inflammation of small arteries and veins is characteristic F - acute necrotising vasculitis affecting small arteries and arterioles. Necrosis and fibrinoid deposits within vessel walls containing antibody, DNA, complement fragments and fibrinogen; transmural and perivascular infiltrate often present. Chronic stages show fibrous thickening with luminal narrowing.

a. Type III hypersensitivity reactions account for most of the systemic lesions T - immune complexes (DNA/anti-DNA), especially in glomeruli.
b. The presence of antibodies to dsDNA is virtually diagnostic T - as is anti-Smith Ag.
c. Discoid rash and oral ulcers are diagnostic criteria T - 11 criteria established by WHO are used for diagnosis. Need 4 or more of these, serially or simultaneously. Others include: malar rash, photosensitivity, nonerosive arthritis, serositis (pleuritis or pericarditis), renal involvement, seizures/psychosis, haematologic disorder, immunologic disorder (eg. anti-DNA, anti-Sm, antiphospholipid Ab’s), positive ANA test.
d. Lupus anticoagulant is a misnomer T - Antiphospholipid syndrome is a hypercoagulable state in vivo: the antibodies induce direct platelet activation and/or interfere with endothelial cell production of prostaglandins. However, in vitro (in the absence of platelets and endothelium) the antibodies interfere with phospholipid complex assembly and thus inhibit coagulation.
e. Inflammation of small arteries and veins is characteristic F - acute necrotising vasculitis affecting small arteries and arterioles. Necrosis and fibrinoid deposits within vessel wals containing antibody, DNA, complement fragments and fibrinogen; transmural and perivascular infiltrate often present. Chronic stages show fibrous thickening with luminal narrowing.

Added options ‘a’, ‘c’, ‘d’; changed ‘b’ from “dsDNA”, and ‘e’ from “arterial & venous involvement”.

Question 31

2. Sep03.05 Systemic sclerosis, which is incorrect:

a. Pulmonary changes are indistinguishable from idiopathic pulmonary fibrosis
b. Telangiectasia is a feature of limited disease
c. The presence of anti-DNA topoisomerase antibodies predicts a more aggressive course
d. Vasculitis is a late feature
e. Raynaud’s phenomenon is often the first manifestation

Answer 31

answer: d. Vasculitis is a late feature F - microvascular disease is consistently present early.
2. Sep03.05 Systemic sclerosis, which is incorrect: (GC)
a. Pulmonary changes are indistinguishable from idiopathic pulmonary fibrosis T - basal predominance, look for the dilated oesophagus.

**LJS - can get UIP pattern (but NSIP most common), in which case it is distinguishable from IPF

b. Telangiectasia is a feature of limited disease T - scleroderma may be diffuse, or limited (=CREST: calcinosis, Raynaud’s, oesphageal dysmotility, sclerodactyly, telangiectasia).
c. The presence of anti-DNA topoisomerase antibodies predicts a more aggressive course T - aka anti-Scl70, highly specific; present in up to 70% of patients with diffuse scleroderma (and <1% of those with other CTD). Marker for patients likely to develop more aggressive disease with pulmonary fibrosis and peripheral vascular pathology.
d. Vasculitis is a late feature F - microvascular disease is consistently present early.
e. Raynaud’s phenomenon is often the first manifestation T - almost all pts develop Raynauds. [Robbins, Ch 5]

Added options a, b, c, e.

Question 32

3. Sep03.06 Fragile X, which is incorrect:

a. Trinucleotide repeat mutation of a gene found on the X chromosome.
b. Long face with large mandible
c. Hyperextensible lax joints
d. Mental retardation
e. 20% of males appear normal

Answer 32

Answer: 20% of males appear normal (incorrect) - technically only applicable in “carrier males”.

ROBBINS - Fragile X
- Trinucleotide (CGG) repeat mutation in the familial mental retardation-1 (FMR1) gene.
- 2nd most common genetic cause of mental retardation after Down syndrome.

Physical characteristic include
- Long face with large mandible
- large everted ears
- Large testicles (macro-orchidism)

Additional features include:
- hyperextensible joints
- high arched palate
- MV prolapse.

The most distinctive features is macro-orchidism, which is observed in at least 90% of affected post-pubertal males.

Although an X-linked recessive disorders, there are some patterns of transmission not typically associated with other X-linked recessive disorders. These include the following:
- Carrier males: Approximately 20% of males who, by pedigree analysis and by molecular tests, are known to carry a fragile X mutation, are clinically and cytogenetically normal.

Question 33

4. Sep03.16 Paget’s disease characteristics, which is false:

a. Large multinucleated osteoclasts in the lytic phase
b. Characteristic woven bone
c. Thought to be caused by a chronic rotaviral infection
d. Raised urine hydroxyproline, normal serum phosphorus
e. Malignant transformation into chondrosarcoma

Answer 33

Answer: Characteristic woven bone (false)

ROBBINS
- Large multinucleated osteoclasts in the lytic phase
- The hallmark is a mosaic pattern of lamellar bone, seen in the sclerotic phase.
- Cultures studies suggest chronic infection of osteoclast precursors by measles, RNA viruses or paramyxovirus. (Rotavirus is an RNA virus).
- Alkaline phosphatase normal in majority of patients. Elevated urinary hydroxyproline.
- 1% risk of malignant transformation. (MFH, Osteosarcoma, Fibrosarcoma, Chondrosarcoma).

Question 34

6. Sep03.44 Suspected NAI, which is most concerning:

a. SIDS of a sibling 13 months old
b. Healing fracture of the clavicle at 1 month
c. Brachial plexus injury
d. Symmetrical periosteal reaction of distal femora
e. Bilateral irregularity of distal metaphyses

Answer 34

6. Sep03.44 Suspected NAI, which is most concerning: (GC)
   ANSWER:a. SIDS of a sibling 13 months old T

a. SIDS of a sibling 13 months old T
b. Healing fracture of the clavicle at 1 month F - healing starts at 1 week and finish at 3 month (for birth trauma)
c. Brachial plexus injury F - may be related to birth trauma.
d. Symmetrical periosteal reaction of distal femora F - differential includes NAI (large subperiosteal haematomas), but many other causes to consider, particularly if bilateral and symmetrical. Scurvy, trauma, infection (TORCH, syphilis), neoplasm (metastatic neuroblastoma, lymphoma), Caffey’s, Kinky hair, PgE therapy, sickle cell disease, hypervitaminosis A & D…

e. Bilateral irregularity of distal metaphyses F - NAI probably less likely if bilateral.
CHARMS: congenital infection (rubella, syphilis), copper deficiency, hypophosphatasia, achondroplasia, rickets, metaphyseal dysostosis, scurvy. [Dahnert]

Question 35

7. Sep03.67 Synovial sarcoma, which is most correct:

a. Calcification uncommon
b. Most common in tendon sheaths of fingers/toes
c. Originates from synoviocytes
d. Peak age 50-60 years old
e. Rarely involves the joint cartilage

Answer 35

7. Sep03.67 Synovial sarcoma, which is most correct: (GC)
   ANSWER:e. Rarely involves the joint cartilage T - lesion is usually about 1cm removed from joint cartilage, <10% involve joint. [Robbins, Dahnert 6th p166, Adelaide notes]

a. Calcification uncommon F - amorphous calcification in 30%, often at periphery. More likely to be calcified than other forms of mesenchymal sarcoma.
b. Most common in tendon sheaths of fingers/toes F - most common around knee. Other sites include hip, ankle (2/3 lower extremity), elbow, wrist, hands & feet, parapharyngeal region, abdominal wall.
c. Originates from synoviocytes F - malignant tumour of mesenchymal cell origin, actual cell of origin unclear. Resembles developing synovium.
d. Peak age 50-60 years old F - 20-40 yo.
e. Rarely involves the joint cartilage T - lesion is usually about 1cm removed from joint cartilage, <10% involve joint. [Robbins, Dahnert 6th p166, Adelaide notes]

Question 36

1. Feature most diagnostic of Gout?

a. Acute pain in 1st MTP joint
b. Negatively birefringent crystal on aspirate
c. Para articular erosions
d. Hyperuricaemia

Answer 36

1. Feature most diagnostic of Gout? (GC)
   ANSWER: b. Negatively birefringent crystals on aspirate. T - definitive diagnosis

a. Acute pain in first metatarsophalangeal joint. F - only 50% of first attacks occur in big toe
b. Negatively birefringent crystals on aspirate. T - definitive diagnosis

c. Para articular erosions. F - with overhanging margins are a hallmark of chronic tophaceous gout (occurs ~12 yrs after 1st acute attack)
d. Hyperuricaemia. F - supports diagnosis, but gout can occur without hyperuricaemia

Question 37

5. Which is incorrect in regards to PVNS?
6. Ankle commonest site
7. Benign neoplastic process
8. Causes erosions
9. Gives rise to haemosiderin deposits in joints.

Answer 37

5. Which is incorrect in regards to PVNS? (GC) ANSWER:a. Ankle commonest site. F - knee affected in 80%
   a. Ankle commonest site. F - knee affected in 80%
   b. Benign neoplastic process. T - cytogenetic studies show consistent chromosomal changes that prove they are neoplastic clonal proliferations. (Robbins)
   c. Causes erosions. T - may erode bone in tighter joints (eg. hip)
   d. Gives rise to haemosiderin deposits in joints. T - hence low on T1 and T2

Question 38

7. Serum electrophoretic analysis and urinary Bence Jones protein assessment are normal. Which of the following statements is most correct:

a. The findings exclude multiple myeloma
b. 1 in 100 cases of multiple myeloma would fit this pattern
c. 20% of case of multiple myeloma would fit this pattern
d. Bence Jones protein assessment should have done on serum
e. In approximately 70% of patients the electrophoretic pattern alone is normal

Answer 38

7. Serum electrophoretic analysis and urinary Bence Jones protein assessment are normal. Which of the following statements is most correct: (GC)

ANSWER:b. 1 in 100 cases of multiple myeloma would fit this pattern T - 1% are non-secretory.

a. The findings exclude multiple myeloma F - absence of paraproteinemia/paraproteinuria does not exclude myeloma.
b. 1 in 100 cases of multiple myeloma would fit this pattern T - 1% are non-secretory.
c. 20% of case of multiple myeloma would fit this pattern F
d. Bence Jones protein assessment should have done on serum F - excreted by the kidney.
e. In approximately 70% of patients the electrophoretic pattern alone is normal F - increased Ig levels in blood, urine, or both in 99%; blood + urine 60-70%; urine alone 20%.

Question 39

8. Ewings sarcoma versus osteomyelitis, less likely Ewings if:

a. Fever
b. Afro-American
c. Involves ilium
d. Regional lymphadenopathy
e. Pathological fracture

Answer 39

Ewings sarcoma versus osteomyelitis, less likely Ewings if: (GC)
ANSWER:b. Afro-American T - 96% of Ewing’s sarcoma occurs in Caucasians

a. Fever F - Ewing’s may present with fever, leukocystosis and anaemia
b. Afro-American T - 96% of Ewing’s sarcoma occurs in Caucasians
c. Involves ilium F - involves flat bones in 40% (predominant location in >20 yo)
d. Regional lymphadenopathy F - present in up to 30% of Ewing’s at time of diagnosis
e. Pathological fracture F - may complicate both Ewing’s and OM [Dahnert 6th, p75] Added options ‘d’ and ‘e’

Question 40

9. Least likely associated with bone aneurysm:

a. Marfan’s
b. NF-1
c. SLE

Answer 40

ANSWER: SLE.

Least likely associated with bone aneurysm: (GC)

a. Marfan’s  T - ?? MSK abnormalities include: kyphoscoliosis, Schmorl's nodes, spondylolisthesis, dural ectasia, pectus deformity, protrusio acetabuli, arachnodactyly, pes planus, SUFE, recurrent discolations. 
Can't find anything about bone cysts!!! 
Chromosome 15 (fibrillin gene), ABCs may be associated with rearrangements in 16q22... 

b. NF-1 T - may see single/multiple cystic lesions within bone. ABCs may be associated with rearrangements of chromosome 17p13; thus mutation of the chromosome may play an important role in the development of NF-1 and ABCs (Surg Neurol 2006). Other skeletal changes in NF-1 include sphenoid dysplasia (bare orbit/harlequin appearance), kyphoscoliosis, posterior vertebral scalloping (dural ectasia), anterolateral bowing of tib/fib +/- pseudoarthrosis, bone erosion from nearby neurofibromas, intramedullary longitudinal streaks of increased density, multiple NOFs, focal gigantism.
c. SLE F - bone changes comprise AVN, insufficiency fracture, infection; due to vasculopathy and/or corticosteroid use.

Question 41

12. Myeloma diagnosed on x-ray, normal plasma electrophoresis with negative bence jones proteins in urine. Which is false:
13. 1% patients with multiple myeloma are negative secretors
14. Patient likely has Waldenstrom’s
15. Patient may be anaemic.
16. Patient may present with confusion.

Answer 41

12. Myeloma diagnosed on x-ray, normal plasma electrophoresis with negative Bence Jones proteins in urine. Which is false: [AB]

ANSWER:2. Patient likely has waldenstroms (FALSE. Waldenstrom is a ddx for MM. Normally no bony lesion. and differentiation

1. 1% patients with multiple myeloma are negative secretors
2. Patient likely has waldenstroms
3. Patient may be anaemic.
4. Patient may present with confusion.

99% of myeloma patients have abnormal urine (BJ proteins - light chains) or serum (M spike - single immunoglobulin) electrophoresis.

Waldenstrom macroglobulinaemia is another monoclonal gammopathy, and would have similar findings. It is associated with lymphoplasmacytic lymphoma.

Myeloma patients may be anaemic (extensive marrow involvement) or have neurologic effects from hypercalcaemia.

Question 42

13. Sclerotic lesion thought to be Paget’s. Least likely:
14. Japanese tourist
15. Female
16. Lytic lesion in same bone
17. Cranial nerve palsies

Answer 42

answer: A

Paget disease is very rare in the Asian population. There is only a slight male predominance.

Lytic lesions in the same bone may reflect the mixed phase of the disease or sarcomatous degeneration (about 1%, higher in polyostotic disease).
Cranial nerve palsies are an uncommon but classic presentation.

Question 43

14. LCH. Which is false:
15. Letterer-Siwe can result in punched out skull lesions
16. Letterer-Siwe 2-7 yo
17. Can present in skull in teenager
18. Is associated with diabetes insipidus

Answer 43

ANSWER: 2. Letterer-Siwe 2-7 yo

EG, the most common form of LCH, can present up to age 30 with the skull most frequently affected.

Letterer-Siwe, the least common form of LCH, presents before age 2 with prominent extraosseous involvement.

The skull can have multiple lytic lesions causing “raindrop skull”.

Hand-Schuller-Christan, the third form, classically (50%) causes diabetes insipidus due to mass effect on or direct infiltration of the posterior pituitary.

Reference: Dahnert, Robbins Changed question to which is false. Changed option 4 - previously “Most frequent to least: tibia to skull”; reworded option 1, 3

Question 44

15. 50 yo male, mass 6cms, near knee but not part of bone, calcium ?synovial sarcoma
16. Hx c/w synovial sarcoma
17. Unlikely due to age / sex
18. Unlikely due to clinical hx
19. Unlikely due to position
20. Unlikely due to size

Answer 44

15. 50 yo male, mass 6cms, near knee but not part of bone, calcium ?synovial sarcoma (TW)

ANSWER:1. Hx c/w synovial sarcoma - T - can not discount SS from DDx given findings.

1. Hx c/w synovial sarcoma - T - can not discount SS from DDx given findings.
2. Unlikely due to age / sex - F - Age 10-50yo.
3. Unlikely due to imaging appearances - F - common location near knee. Amorphorus calcification in 30%. Calcification in other soft-tissue connective tissue sarcomas is uncommon.
4. Unlikely due to position - F - Extremities 80-95%: lower extremitiy 60% (knee most common); upper extremity 15%. Juxta articular location 90% (within 5cm of joint). Bone invasion less common (10-20%).
5. Unlikely due to size - F - size 3-8cm. Well defined rounde or lobulated soft tissue mass.

Synovial sarcoma is not of synovial origin, but morphology resembles developing synovium. Thought to originate from undifferentiated mesenchymal tissue (pluripotent mesenchyme of the limb bud). 4th most common soft tissue sarcoma.

DDx: chondrosarcoma (proximal extremities, invasion adjacent skeletal structures); myositis ossificans (dense ossified periphery); PVNS (rarely calcifies); Parosteal OS (periosteal reaction); MFH (rarely calcified, older); Juxtacortical chondroma (involves bone). (Dahnert 6th ed. Stoller Ortho)

Question 45

16. Monoclonal gammopathy need radiology, which is most appropriate:
17. CT Chest, Abdo and Pelvis
18. CT Head, Neck and CAP
19. Plain film axial skeleton and proximal limbs
20. Plain film axial skeleton and hands
21. Plain films of axial skeleton and bone marrow aspirate

Answer 45

16. Monoclonal gammopathy need radiology, which is most appropriate: (TW)
    ANSWER:3. Plain film axial skeleton and proximal limbs - T - most appropriate answer. Skeletal assessment for lytic lesions primarily to exclude multiple myeloma. Although bone marrow aspirate may be warranted, there are times when it’s not required (see below).
17. CT Chest, Abdo and Pelvis
18. CT Head, Neck and CAP
19. Plain film axial skeleton and proximal limbs - T - most appropriate answer. Skeletal assessment for lytic lesions primarily to exclude multiple myeloma. Although bone marrow aspirate may be warranted, there are times when it’s not required (see below).
20. Plain film axial skeleton and hands
21. Plain films of axial skeleton and bone marrow aspirate - Need to Dx monoclonal gammopathy (of uncertain significance MGUS) from multiple myeloma, and polyclonal gammopathy.

MGUS carris risk of progress to myeloma of 1% / yr. -

MGUS vs MM - MGUS has absence of symptoms; low M component (IgA, IgG, or IgM) <3g/dL; fewer than 10% plasma cells in bone marrow, and absence of lytic lesions, anemia, hypercalcemia, and renal insufficiency. - Minimal initial studies for evaulation of MGUS - CBC, serum Ca+ / Cr, serum EPP, quantitation of immunogloulins, urinalysis / 24hr urine, metastatic bone survey.

• BMAT if M protein >1.5g/dL, patient has a non-IgG MGUS, or there is an abnormal free light chain ratio. Also in pts with unexplained anemia, renal failure, hypercalcemia, or bone lesions on metastatic bone survey. - pts with an IgM monoclonal protein should have abdo CT (as asymptomatic retroperitoneal lymph node enlargement may be present). (UpToDate)

Question 46

Giant cell

1. 5-10% sarcomatous
2. Intermediate
3. Mets to lung

Answer 46

c. 0.5 – 5% Mets to lung

GCT

• benign
• but locally aggressive neoplasm.
• Can recur after conservative surgery/curettage.
• 4% metastasize to lungs.
• Sarcomatous transformation is rare. (Robbins)

Question 47

2. Amyloidosis which is NOT correct
3. 2-5% cause renal disease
4. Is associated with TB
5. 40% associated with haemodialysis
6. have types call lardaceous spleen and sago spleen
7. RA 5%

Answer 47

a. 2-5% cause renal disease
ANSWER:
1. F – amyloidosis of the kidney is the most common form of organ involvement, causing proteinuria and nephrotic syndrome with CRF and uraemia. (Robbins)

b. Is associated with TB T – secondary amyloidosis is associated with TB, bronchiectasis, osteomyelitis, RA, AS, IBD, RA, haemodialysis (Robbins).
c. 40% associated with haemodialysis ?T – not sure about the figures but 60-80% of patients on long term dialysis have amyloid deposits in synovium, joints and tendon sheaths. (Robbins).
d. have types call lardaceous spleen and sago spleen T – Sago spleen: amyloid deposits producing tapioca-like granules on gross inspection. Lardaceous spleen: fusion of these deposits gives rise to maplike areas. (Robbins)
e. RA 5% T – amyloid occurs in 3% of patients with RA (Robbins).

Question 48

3. Femur with OS and abnormal distal femur not associated with
4. Pagets
5. Fibrous dysplasia
6. Renal osteodystrophy
7. Radiation
8. Bone infarct

Answer 48

3. Femur with OS and abnormal distal femur not associated with: (JS, with TW & GC)

ANSWER:3. RENAL OSTEODYSTROPHY

a. Pagets T – sarcomatous transformation in 1%
b. Fibrous dysplasia T - rare
c. Renal osteodystrophy F
d. Radiation T – 10-12 y latency period
e. Bone infarct T – rare

Question 49

4. CNs(cranial nerves?) and Pagets ( false )
5. Increase bone decreased mineral density
6. Sarcoma of bone
7. Softening of bone
8. Foraminal narrowing

Answer 49

a. Increase bone, decreased mineral density
*LW: Robbins states net effect of Paget reaction is gain in bone mass, however new bone is disordered with soft cortices, and lacks strength.
Thus options 2, 3, 4 are are all true, and bone mineral density is a measure of bone mass, hence bone mineral density likely increased rather than decreased.

CNs(cranial nerves?) and Pagets, which is false: (JS) answer:

a. Increase bone, decreased mineral density F?? - I’m not sure about this one – Pagets does cause an increase in bone mass, especially in the blastic phase. A few articles have stated that there can be focally increased bone mineral density within vertebrae affected by Pagets, but non-affected vertebrae can show decreased BMD. Bisphosphonates are used in treatment and lead to an increase in BMD – so maybe the answer is true!!
b. Sarcoma of bone T – sarcomatous transformation occurs in 0.7 – 0.9% of all patients with Pagets but up to 10% in those with polyostotic disease (Robbins)
c. Softening of bone T – Bones are larger with coarsely thickened trabeculae and cortices that are soft and porous and lack structural stability (Robbins).
d. Foraminal narrowing T – bone overgrowth can compress spinal and cranial nerve roots in base of skull (Robbins).

Question 50

5. Gout , least likely
6. AC joint
7. Negatively Birefringent
8. 1st MTP
9. Renal Calculi
10. Hyperuricaemia

Answer 50

Gout , which is least likely (JS) answer:
a. AC joint involvement

a. AC joint involvement F - Typical joints involved include MTP, ankles, heels, knees, wrist, fingers and elbows (Robbins)
b. Negatively birefringent crystals
c. 1st MTP joint
d. Renal calculi T - Renal manifestations include uric acid renal stones and renal colic with 20% dying of chronic renal failure (Robbins)
e. Hyperuricaemia

Question 51

1. Least likely associated with bone aneurysm:

a. Marfan’s
b. NF-1
c. SLE

Answer 51

1. Least likely associated with bone aneurysm: (GC) answer: SLE
   a. Marfan’s T - ?? MSK abnormalities include: kyphoscoliosis, Schmorl’s nodes, spondylolisthesis, dural ectasia, pectus deformity, protrusio acetabuli, arachnodactyly, pes planus, SUFE, recurrent discolations. Can’t find anything about bone cysts!!! Chromosome 15 (fibrillin gene), ABCs may be associated with rearrangements in 16q22…
   b. NF-1 T - may see single/multiple cystic lesions within bone. ABCs may be associated with rearrangements of chromosome 17p13; thus mutation of the chromosome may play an important role in the development of NF-1 and ABCs (Surg Neurol 2006). Other skeletal changes in NF-1 include sphenoid dysplasia (bare orbit/harlequin appearance), kyphoscoliosis, posterior vertebral scalloping (dural ectasia), anterolateral bowing of tib/fib +/- pseudoarthrosis, bone erosion from nearby neurofibromas, intramedullary longitudinal streaks of increased density, multiple NOFs, focal gigantism.
   c. SLE F - bone changes comprise AVN, insufficiency fracture, infection; due to vasculopathy and/or corticosteroid use.

Question 52

1. Feature most diagnostic of Gout?

a. Acute pain in 1st MTP joint
b. Negatively birefringent crystal on aspirate
c. Para articular erosions
d. Hyperuricaemia

Answer 52

1. Feature most diagnostic of Gout? (GC)
   answer : B Negatively birefringent crystals on aspirate. T - definitive diagnosis

a. Acute pain in first metatarsophalangeal joint. F - only 50% of first attacks occur in big toe
b. Negatively birefringent crystals on aspirate. T - definitive diagnosis
c. Para articular erosions. F - with overhanging margins are a hallmark of chronic tophaceous gout (occurs ~12 yrs after 1st acute attack)
d. Hyperuricaemia. F - supports diagnosis, but gout can occur without hyperuricaemia

Question 53

1. Chondromyxoid fibroma question:
2. 25yo female with metaphyseal lesion at site of a previous ABC
3. 20 yo male involving the metaphysis
4. 5 yo with Epiphyseal lesion
5. Another answer specifying an Epiphyseal location

Answer 53

8. Chondromyxoid fibroma, which of these is most likely: (JS)
   answer: b. 20 yo male involving the metaphysis T - Typical location is metaphysis (50%) and in the 2nd to 3rd decade (Dahnert). *LW: Robbins states age is teens - 20s, with male predominance.

a. 25yo female with metaphyseal lesion at site of a previous ABC F - ABC can arise in a pre-existing bone lesion, not visa versa (Dahnert)
b. 20 yo male involving the metaphysis T - Typical location is metaphysis (50%) and in the 2nd to 3rd decade (Dahnert)
c. 5 yo with Epiphyseal lesion F - Rare within the epiphysis
d. Another answer specifying an Epiphyseal location F

Question 54

Features of Gout, which is correct?

a. Renal failure is a common cause of death in patients with chronic gout.
b. Hyperuricaemia in 50% of 50 year old males.
c. Chronic tophi in 10%.
d. Presentation with polyarticular arthritis.

Answer 54

42. Features of Gout, which is correct? (GC)

Answer:a. Renal failure is a common cause of death in patients with chronic gout.T - death from renal failure in 20%

a. Renal failure is a common cause of death in patients with chronic gout.T - death from renal failure in 20%
b. Hyperuricaemia in 50% of 50 year old males.F - over 10% of western population have hyperuricaemia (Adelaide notes)
c. Chronic tophi seen in 10%.F - about half of patients who have had attacks of gout for >10yrs develop tophi. (Emergency Orthopedics, R Simon)
d. Presentation with polyarticular arthritis.F - vast majority of first attacks are monoarticular (50% great toe)

Question 55

43. Which is most correct regarding the pathogenesis of Rheumatoid arthritis?

a. Interleukins are involved.
b. Infection is a trigger.
c. Immune complexes play a pivotal role in the process.
d. Cross reaction occurs with hydroxyapatite crystals.

Answer 55

ANSWER: A
a. Interleukins are involved.T - CD4+ helper T cells produce cytokines (eg. TNF), that activate macrophages and B cells. Activated macrophages produce IL-1, resulting in proliferation of synovial cells and fibroblasts). IL-1 and TNF also account for the constitutional symptoms (fever, malaise, weakness) that may be seen in RA.

43. Which is most correct regarding the pathogenesis of Rheumatoid arthritis? (GC)
    a. Interleukins are involved.T - CD4+ helper T cells produce cytokines (eg. TNF), that activate macrophages and B cells. Activated macrophages produce IL-1, resulting in proliferation of synovial cells and fibroblasts). IL-1 and TNF also account for the constitutional symptoms (fever, malaise, weakness) that may be seen in RA.
    b. Infection is a trigger.F - thought to be triggered by exposure of a genetically predisposed individual to an arthitogenic agent, possibly microbial. Adelaide notes state that EBV (and other microbial agents) have been postulated but firm evidence of a microbial trigger is not available.
    c. Immune complexes play a pivotal role in the process.F - 80% of RA patients have rheumatoid factor - a serum IgM autoantibody that binds to the Fc portion of the body’s own IgG. RF immune complexes form in sera, synovial fluid and membranes. However, 20% do not have RF, suggesting that these autoantibodies are not essential for tissue injury in RA (Robbins). Circulating IC’s contribute to extra-articular disease and may have a role in joint destruction (Adelaide notes).
    d. Cross reaction occurs with hydroxyapatite crystals.F - not considered a pathogenetic variable. Changed Q from “which is true”, changed c from “IC’s are involved”.

Question 56

44. Osteosarcoma would not be seen as a complication of the following in a 50 yr old man?

a. Pagets.
b. Radiation.
c. Renal osteodystrophy.
d. Bone infarct.
e. Fibrous dysplasia.

Answer 56

c. renal osteodystrophy T
- other benign tumours in which OSA can arise include hereditary osteochondromas, enchondroma (TW)

OS developing in fibrous dysplasia is a rare event occurring in about 0.5% to 1%.

Secondary OS associated with medullary bone infarcts seem to be even more rare, with about 50 patients with sarcomas arising in bone infarcts being reported (Differential diagnosis in orthopaedic oncology, Greenspan).

Question 57

1. Which is most correct in regards to fibrous dysplasia
2. Benign bone lesion with all components of normal bone present
3. Benign bone lesion with metaplasia of connective tissue
4. Benign bone lesion with abnormal giant cells
5. Benign bone lesion with multiple thin blood-filled cystic cavities
6. Benign bone lesion with excessive fibrous proliferation

Answer 57

1. Which is most correct in regards to fibrous dysplasia (TW)
   ANSWER:1. Benign bone lesion with all components of normal bone present - T - benign lesion due to a localised development arrest in which all the component of normal bone are present but do not differentiate into their mature structures (path notes). Defect in osteoblastic differentiation and maturation (D 6th).
2. Benign bone lesion with all components of normal bone present - T - benign lesion due to a localised development arrest in which all the component of normal bone are present but do not differentiate into theri mature structures (path notes). Defect in osteoblastic differentiation and maturation (D 6th).
3. Benign bone lesion with metaplasia of connective tissue - F - Myositis ossificans - general term which refers to heterotopic soft tissue ossification with several aetiologies. It is due to metaplasia of intermuscular connective tissue and not to muscle inflammation (path notes)
4. Benign bone lesion with abnormal giant cells - F - GCT has osteoclast type multinucleated giant cells scattered evenly throughout tissue. Giant cells can also be seen in brown tumor, giant cell reparative granuloma, chondroblastoma, PVNS.
5. Benign bone lesion with multiple thin blood-filled cystic cavities - F - ABC
6. Benign bone lesion with excessive fibrous proliferation - F - although FD may have moderately cellular fibroblastic proliferation, see fibrous proliferation with the various fibrous and fibro-osseous tumors (Robbins), eg. FCD, NOF, benign fibrous histiocytoma.

Question 58

2. Which demonstrates a hyperplastic synovium
3. Acute Gout
4. Rheumatoid arthritis
5. Osteoarthritis
6. Myositis ossificans
7. CPPD

Answer 58

ANSWER:2. Rheumatoid arthritis

2. Which demonstrates a hyperplastic synovium (TW)
3. Acute Gout - F - supersaturation of synovial fluid with MSU. Microtophi in synovial cells. Acute stage - get oedematous and congested synovium. In chronic tophaceous arthritis of gout, get hyperplastic synovium (path notes).
4. Rheumatoid arthritis - T - thick, oedematous hyperplastic synovium (path notes)
5. Osteoarthritis - F - Articular cartilage is major cause of degenerative change in OA. synovium shows minor alterations in comparsion to the destruction of the articular surface and is congested and fibrotic. Nonspecific synovitis without pannus. (Robbins / Path notes)
6. Myositis ossificans - F - metaplasia of intermuscular connective tissue and not to muscle inflammation (path notes)
7. CPPD - F

Question 59

3. CPPD is not a feature of which of the following
4. Pseudogout
5. Chondrocalcinosis
6. Gout
7. Haemochromatosis
8. ochronosis

Answer 59

3. CPPD is not a feature of which of the following (TW)
   answer: GOUT

**LJS - RP says all of these can have chondrocalcinosis
Gout and ochronosis less common

1. Pseudogout - T - AKA CPPD. Relatively common disorder with intra-articular crystal formation. Accumulation of pyrophosphate, crystallization of pyrophosphate with calcium. crystals develop in articular matrix, menisci and intervertebral discs first. Calcium pyrophosphate.
2. Chondrocalcinosis - T - AKA CPPD.
3. Gout - F - monosodium urate crustals cf calcium pyrophosphate crystals. Gout: Synovial fluid poorer solvent for MSU than plasma. Supersaturation in joint fluid. Get microtophi in synovial cells and articular cartilage (incl menisci).
4. Haemochromatosis - T - Secondary CPPD
5. ochronosis - T - Secondary CPPD. AKA alkaptonuria - inherited absence of homogentistic acid oxidase with excessive homogentisic acid production and deposition in connective tissue (incl. cartilage, synovium, and bone)

Causes of secondary CPPD - joint damage, hyperparathyroidism, haemochromatosis, hypomagnesemia, hypothyroidism, ochronosis, diabetes (path notes).

Question 60

4. Foreign body giant cells arise in
5. Rheumatoid arthritis
6. Gout
7. Psoriasis
8. Reiter’s
9. Ankylosing spondylitis

Answer 60

4. Foreign body giant cells arise in (TW)
   answer: 2 Gout - T - tophi are hallmark of gout - represent large aggregations of urate crystals - surrounded by intense inflammatory reaction of macrophages, lymphocytes, and foreign body giant cells (path notes)
5. Rheumatoid arthritis - F - Cause unknown. Autoimmunity has a role. Non-specific inflammation. Dense perivascular inflammatory infiltrate rich in CD4+ helper T cells fill synovial stroma. Neutrohils accumulate in synovial fluid and along synovial surface.
6. Gout - T - tophi are hallmark of gout - represent large aggregations of urate crystals - surrounded by intense inflammatory reaction of macrophages, lymphocytes, and foreign body giant cells (path notes)
7. Psoriasis - F - Aetiology not defined ?genetic predisposition. Get papillary hyperplasia of synovium. Lymphocyte and plasma cell infilatration.
8. Reiter’s - F - Diagnotic triad: arthritis; preceding nongonococcal urethritis or cervicitis, bacillary dysentery; conjunctivitis. Aetiology - autoimmune initiated by prior infection. Involvement of synovial joints, symphyses, enthesis. Non specific neutrophil infiltrate, oedema of synovium.
9. Ankylosing spondylitis - F - Aetiology - genetic predisposition + environmental stimulating factor / arthriogen. Autoantibodies.

Question 61

5. Which is most characteristic of an adamantioma
6. Multicystic (soapbubble) osteolytic
7. Onion skin periosteal reaction
8. Increased bone trabecular pattern
9. Involvement of epiphyses
10. osteosclerosis

Answer 61

answer: 1. Multicystic (soapbubble) osteolytic - T - multicystic (“soap bubble”) osteolytic lesion with surrounding sclerosis. Cortical thinning and expansion. May see skip lesion (path notes).
5. Which is most characteristic of an adamantinoma (TW)
1. Multicystic (soapbubble) osteolytic - T - multicystic (“soap bubble”) osteolytic lesion with surrounding sclerosis. Cortical thinning and expansion. May see skip lesion (path notes).
2. Onion skin periosteal reaction - F - lamellated periosteal reaction - typically Ewings
3. Increased bone trabecular pattern - F - may see increased pattern in mixed phase of pagets. Micro of fibrous dysplasia - irregular foci of immature woven bone trabeculae.
4. Involvement of epiphyses - F - adamantinoma usually affects jaw bones, but sometimes in long bones (diaphysis). Epiphyses - GCT, chondroblastoma,
5. osteosclerosis - F - secondary hyperparathyroidism.

Question 62

6. Which is most supportive of the diagnosis of gout
7. HGPRT deficiency
8. Periarticular erosions on plain xray
9. Negative birefringent crystals on aspirate
10. Acute arthritis of 1st MTPJ
11. Increased serum urate levels

Answer 62

6. Which is most supportive of the diagnosis of gout (TW)
   answer: 3. Negative birefringent crystals on aspirate
7. HGPRT deficiency - F - hypoxanthine guanine phosphoribosyl transferase deficiency (results in increased synthesis of purine nucleotides). Occurs in (uncommon) X-linked Lesch-Nyhan syndrome, only males: hyperuricemia, neuro deficits, mental retardation, self-mutilation, and some cases gouty arthritis.
8. Periarticular erosions on plain xray - F - gouty erosions can be peri/para-articular / extra-articular, slow progressing so sclerotic edge (+ overhanging margin). Can also see periarticular erosions in RA, psoriasis, and other inflammatory arthridities.
9. Negative birefringent crystals on aspirate - T - MSU crystals are long, slender, and needle shaped and are negatively birefringent.
10. Acute arthritis of 1st MTPJ. - F - gout does involve 1st MTPJ most commonly, but not exclusively.
11. Increased serum urate levels - F - >10% western population have hyperuricaemia, however gout in 0.1 to 0.4%. Article “Gout” - Singapore Med J 1992; 33:393-394.

Most specific (100%) test is the demonstration of characteristic sodium urate monohydrate crystals in joint fluid (however only found in 85% of patients with acute gout).

Question 63

7. Features of a giant cell tumour include
8. Peak incidence 10-20yo
9. Most common in flat bones of the chest and pelvis
10. 10% sarcomatous transformation
11. lung metastases 0.5 – 5%
12. giant cells are monoclonal

Answer 63

7. Features of a giant cell tumour include (TW)

*LW:
4. lung metastases 0.5 – 5%
Robbins states up to 4% metastasize to lungs, hence my preferred answer.

Previous answer: Probably 3
3. 10% sarcomatous transformation - T - sarcomatous transformation 5-10% (D 6th, Path notes).

1. Peak incidence 10-20yo - F - epiphyses closed for GCT. 80% occur between 20-50yo
2. Most common in flat bones of the chest and pelvis - F - Knee 50-65% (distal femur 23-30%, prox tibia 20-25%), distal radius 10-12%, flat bones 15%.
3. 10% sarcomatous transformation - T - sarcomatous transformation 5-10% (D 6th, Path notes)
   * LW - Robbins states sarcomatous transformation is a rare event, so I would assume less than 10%, so hence I feel this answer is FALSE.
4. lung metastases 0.5 – 5% - ?F - although does metastasise to lungs, D6th and path notes say 5% (?F as not 0.5-5%). True SG
5. giant cells are monoclonal - F - cannot find anything to say monoclonal. Histo: multinucleated osteoclastic giant cells in a diffuse distribution in a background of mononuclear cells intermixed throughout a spindle cell stroma.
   * RY - GCT not monoclonal. GCT contains neoplastic cells (giant cells of osteoblast precursor origin), but the majority of the tumour is made up of non-neoplastic osteoclasts and their precursors (including a different type of giant cell). Monoclonality is one of the general principles of a neoplastic population, but here the tumour is heterogeneous given there are both neoplastic and non-neoplastic cells (including within the giant cell population). Robbins/Wiki.

Question 64

8. Morton’s neuroma, which of the following is most correct?
9. Most common between 4th and 5th digits
10. Not a true neuroma
11. Presents as a painful lump
12. Represents axonal degeneration
13. Ethanol ablation is not appropriate

Answer 64

Answer: not a true neuroma

Radiopaedia
- AKA interdigital/intermetatarsal neuroma
- focal area of symptomatic perineural fibrosis around a plantar digital nerve of the foot
- due to chronic entrapment of the nerve by the intermetatarsal ligament
- neuroma is therefore misnomer

Location
- 3rd web space (between 3rd-4th metatarsal heads)
- 2nd web space (between 2nd-3rd metatarsal heads) less often involved.
- 10% of lesions are bilateral

Note:
- 1st intermetatarsal space: Heuter neuroma
- 4th intermetatarsal space: Iseline neuroma

8. Morton’s neuroma, which of the following is most correct? (TW)
   answer: 2. Not a true neuroma - T - MN is perineural fibrosis entrapping a plantar digital nervs; neuroma is a misnomer.
9. Most common between 4th and 5th digits - F - typically 2nd / 3rd intermetatarsal space (rarely 1st / 4th).
   * *LJS - typically 3/4th, less commonly 2nd/3rd - RP
10. Not a true neuroma - T - MN is perineural fibrosis entrapping a plantar digital nervs; neuroma is a misnomer.
11. Presents as a painful lump - F - numbness; burning/tingling electric forefoot pain increasing with activity + wearing of narrow shoes.
    * *LJS - is typically painful
12. Represents axonal degeneration - ?F - exact cause unknown, MN most likely represents an entrapment neuropathy causing perineural fibrosis, nerve degeneration, leukocyte infiltration, and epineural and endoneural vascular hyalinization that results in a significantly thicker intermetatarsal nerve (AJR 2000).
13. Ethanol ablation is not appropriate - F - alcohol injection of MN has a high success rate and is well tolerated (AJR 2007) Added ‘which of the following is most correct’ to Qu.

Question 65

9. Osteosarcoma - which is not a subtype
10. Osteoblastic
11. Round cell
12. Osteoclastic
13. Telangectatic

Answer 65

Answer: Osteoclastic

ROBBINS
Histological subtypes include; osteoblastic, chondroblastic, fibroblastic, telangiectatic, small cell, giant cell.

The most common subtype arises in the metaphysis of long bones, and is primary, intramedullary, osteoblastic, and high grade.

Question 66

10. Chordoma is characterised by
11. Histologic absence of calcification
12. Arises from remnants of nucleus pulposus
13. Physaliferous cells
14. Low recurrence following radical surgery

Answer 66

10. Chordoma is characterised by (TW)

ANSWER:3. Physaliferous cells - T - typical chordoma: cords + clusters of large bubblelike vacuolated (physaliferous) cells containing intracytoplasmic mucous droplets.

1. Histologic absence of calcification - F - amorphous calcification 50-75%
2. Arises from remnants of nucleus pulposus - F - originates from embryonic remnants of nonochord / ectopic cordal foci (nonochord appears between 4th and 7th week of embryonic development, extends from Rathke pouch to coccyx and forms nucleus pulposus)
3. Physaliferous cells - T - typical chordoma: cords + clusters of large bubblelike vacuolated (physaliferous) cells containing intracytoplasmic mucous droplets.
4. Low recurrence following radical surgery - F - almost 100% recurrence rate despite radical surgery

Question 67

1. Giant cell tumors, which of the following is least correct?
2. 5-10% undergo sarcomatous transformation
3. May be associated with Paget disease
4. Consists of multinuclear osteoblastic giant cells in a background of mononuclear cells
5. May find focal ABC components in 10-15% of GCTs
6. May metastasize to lungs

Answer 67

Answer: 1 and 3

ROBBINS
- aka osteoclastoma
- seen in 20-40s age group
- arise in epiphysis, but may extend into metaphysis
- majority arise around the knee.

Histology
- sheets of uniform oval mononuclear cells and numerous multinuclear osteoclast-type giant cells

Clinical course
- treated with curettage
- 40-60% recurrence rate
- 4% metastatize to lungs, but sometimes spontaneously regress, seldom fatal.
- Denosumab (RANKL inhibitor) potential treatment.

Malignant transformation data unknown - not on robbins/statdx/radiopaedia.

Question 68

1. Which is true regarding rheumatoid arthritis?
2. RF is an antibody (IgG) vs the Fc portion of IgM
3. Commonest 5th-7th decades
4. C spine involved in 50%
5. Female to male ratio of 10:1

Answer 68

LJS opinion: Latest Robbins (2018) says peak incidence in 3rd to 5th decades of life i.e. 20-50yr
Radiopedia and stat dx say C-spine involved in 50% (Robbins is vague about this - states “upper spine is uncommonly involved”)
I think 3. is most correct

*LW:
Confusingly Old robbins states most common age 40 -70yrs, i.e. 5th - 8th decades.
Also, C spine involvement has improved with DMARD use, so over all out of date question with debatable answers….

1. Which is true regarding rheumatoid arthritis? (TW)

answer:
2. Commonest 5th-7th decades - T - Peak age 45-65yo (D 6th ed). Peak incidence during 5th to 8th decades (path notes).

1. RF is an antibody (IgG) vs the Fc portion of IgM - F - RF is an autoantibody (IgM, but also IgA, IgE) against Fc portion of IgG (UpToDate).
2. Commonest 5th-7th decades - T - Peak age 45-65yo (D 6th ed). Peak incidence during 5th to 8th decades (path notes).
3. C spine involved in 50% - ?F - Cervical spine involvement in RA is common, up to 90% (Wheelesonline). Frequency of radiographic signs of involvement of cervical area is in the range of 43-86% depending on the duration of the disease (eMedicine).
4. Female to male ratio of 10:1 - F - M:F 1:3 if <40yo. 1:1 if >40yo (Dahnert 6th).

Question 69

2. Which is true regarding enchondromas?
3. Increased prevalence of ovarian Ca and CNS glioma with Olliers disease
4. Generally always contain ring & arc type calcifications
5. More likely to be found in the distal phalanx than the proximal phalanx
6. Solitary more common than multiple

Answer 69

2. Which is true regarding enchondromas? (TW) answer:
3. Solitary more common than multiple - T - usually solitary (D 6th ed).
4. Increased prevalence of ovarian Ca and CNS glioma with Olliers disease - F - Increased prevalence of ovarian carcinoma, pancreatic carcinoma, CNS gioma, and GIT adenocarcinoma with Maffucci’s syndrome (D 6th ed.)
5. Generally always contains ring & arc type calcifications - F - B&H - must have Ca++ unless in phalages.
6. More likely to be found in the distal phalanx than the proximal phalanx - F - 40% small tubular bones of wrists and hand (most frequent tumor here), distal and mid aspects of metacarpals, proximal / middle phalanges (D 6th ed).
7. Solitary more common than multiple - T - usually solitary (D 6th ed).

Question 70

3. Which is true regarding aneurysmal bone cysts?
4. 60% found in the spine
5. Metaphyseal when found in a long bone
6. > 50% associated with GCT
7. 50% associated with other lesions

Answer 70

3. Which is true regarding aneurysmal bone cysts? (TW)
   answer: 2. Metaphyseal when found in a long bone - T - eccentric in metaphysis in long bone (femur, tibia, humerus, fibula) (path notes / D 6th ed)
4. 60% found in the spine - F - 30% (path notes)
5. Metaphyseal when found in a long bone - T - eccentric in metaphysis in long bone (femur, tibia, humerus, fibula) (path notes / D 6th ed)
6. > 50% associated with GCT - F - of the 30% of all ABC’s, 40% of these arise in GCT’s (which = 12% total, path notes). 14% GCTs may have focal ABC components in tumor centre (D 6th ed).
7. 50% associated with other lesions - F - primary ABC 70%.
   30% ABCs arise in preexisting bone tumors. i.e30 % in spine30 % a/w other tumour13-14% a/w GCT

Question 71

4. Pseudogout is associated with…
5. Hyperthyroidism
6. Hypermagnesemia
7. Positively birefringent crystals
8. Negatively birefringent crystals

Answer 71

4. Pseudogout is associated with… (TW) answer: positive birefringent
5. Hyperthyroidism - F - CPPD is associated with hyperparathyroidism, hypothyroidism, hemochromatosis, hypomagnesemia.
6. Hypermagnesemia - F
7. Positively birefringent crystals - T - CPPD crystals are rod-shaped with blunt ends / rhomboid shape; are positively birefringent. Pragmatically, this means that their colors are opposite those of gout. Thus, pseudogout crystals are blue when aligned parallel to the slow ray of the compensator and yellow when they are perpendicular.
8. Negatively birefringent crystals - F - negatively birefringent crystals are diagnostic of gout. Urate crystals are negatively birefringent, meaning that the crystals are yellow when aligned parallel to the slow ray of the compensator and that they are blue when they are perpendicular.

Question 72

5. Which is true regarding osteoporosis?
6. Postmenopausal osteoporosis is more common in women than men by a ratio of 20:1
7. Can occur secondary to malignancy
8. Postmenopausal osteoporosis is characterised by increased osteoblastic activity and decreased bone turnover
9. Is characterised by reduced bone mass and abnormal composition

Answer 72

5. Which is true regarding osteoporosis? (TW) answer: 2. Can occur secondary to malignancy - T - Primary osteoporosis (postmenopausal, age-related). Secondary (endocrine disorder, neoplasia, GI, rheumatoligc, drugs, miscellaneous)
6. Postmenopausal osteoporosis is more common in women than men by a ratio of 20:1 - F - postmenopausla 6:1 F:M. Age related osteoporosis 2:1 F:M.
7. Can occur secondary to malignancy - T - Primary osteoporosis (postmenopausal, age-related). Secondary (endocrine disorder, neoplasia, GI, rheumatoligc, drugs, miscellaneous)
8. Postmenopausal osteoporosis is characterised by increased osteoblastic activity and decreased bone turnover - F - increased osteoclast activity. Increase resorption. Essentially “high turnover” form of osteoporosis. Decreased oestrogen - increased IL-1 by blood moncytes - stimulator osteoclast recruitment and activity.
9. Is characterised by reduced bone mass and abnormal composition - F - reduced bone mass of normal composition. (path notes)

Question 73

6. Which is true regarding osteosarcoma?
7. Classically has an onion-skin periosteal reaction
8. A fine radiolucent line separating periosteal osteosarma tumor mass from cortex may be seen in 30-40%
9. Can arise from Pagets disease
10. Can arise from previous irradiation within 2y.

Answer 73

6. Which is true regarding osteosarcoma? (TW) answer:
7. Can arise from Pagets disease - T - Pagets disease - Associated neoplasia (up to 20%): sarcomatous transformation into osteosarcoma (22-90%), fibrosarcoma / MFH (29-51%), chondrosarcoma (1-15%) - (Dahnert 6th ed.)
8. Classically has an onion-skin periosteal reaction - F - onion-skin is classically assoc with Ewings. OS can still have this reaction, along with sunburst, and Codman’s triangle.
9. A fine radiolucent line separating periosteal osteosarcoma tumor mass from cortex may be seen in 30-40% - F - this applies to paraosteal (juxtacortical) osteosarcoma (Path notes)
10. Can arise from Pagets disease - T - Pagets disease - Associated neoplasia (up to 20%): sarcomatous transformation into osteosarcoma (22-90%), fibrosarcoma / MFH (29-51%), chondrosarcoma (1-15%) - (Dahnert 6th ed.)
11. Can arise from previous irradiation within 2y - F - time interval about 10-12y (other cause if <2y). dose >3000rads (Path notes).

Question 74

6. Ewings sarcoma

a. 15-20 yo most commonly
b. Early hepatic metastasis recognised
c. Differential Chondrosarcoma
d. Occurs in metaphysis of long bones
e. Differential is Neuroblastoma

Answer 74

6. Ewings sarcoma (TW)
   answer: - ddx of neuroblastoma
   a. 15-20 yo most commonly - F - peak age 15yo. 30% <10yo. 39% 11-15yo. 31% >15yo. *LW: Robbins states most commonly 10-15yrs old.
   b. Early hepatic metastasis recognised - F - mets to lung, bones, regional lymph nodes in 11-30% at time of diagnosis, in 40-45% within 2 years of diagnosis.

c. Differential Chondrosarcoma - F - DDx infection, EG, osteosarc, neuroblastoma <5, multiple myeloma (adult), hodgkin, mets.
Chondrosarcoma (central): neck of femur, pubic rami, prox humerus, ribs - usually central within medullary canal meta-/diaphysis. Large soft-tissue mass.

d. Occurs in metaphysis of long bones - F - less commonly in metaphysis. Metadiaphysis 44%, middiaphysis 33%, metaphysis 15%, metaepiphyseal 6%.
e. Differential is Neuroblastoma - T - see option c.

Question 75

7. Reiters

a. HLA B27 30-50%
b. Female > Male
c. Preceding episode of gonococcal urethritis
d. GI infection
e. 50-70yo most common

Answer 75

7. Reiters (TW) - now known as reactive arthritis. answer:
   d. GI infection - T - Preceeding infection. Enteric bacteria assoc with reactive arthritis include: salmonella, shigella, yersinia, campylobacter, clostridium.

a. HLA B27 30-50% - F - HLA-B27 in 76%
b. Female > Male - F - M>F 98:2
c. Preceding episode of gonococcal urethritis - F - the only genital pathogen commonly accepted to be the cause of reactive arthritis is Chlamydia trachomitis. A number of other bacteria have been reported, however their roles are disputed.
d. GI infection - T - Preceeding infection. Enteric bacteria assoc with reactive arthritis include: salmonella, shigella, yersinia, campylobacter, clostridium.
e. 50-70yo most common - F - typically in young adults.

Question 76

38. Which is true regarding rheumatoid arthritis?

a. Clinically measured rheumatoid factor is IgG
b. Commonest 5th-7th decades
c. C spine involved in 50%
d. Female to male ratio of 10:1

Answer 76

• SD: I prefer c. 50% C spine
  38. Which is true regarding rheumatoid arthritis? (TW) answer:
  b. Commonest 5th-7th decades - T - peak incidence during 4th to 8th decades (path notes). Peak age: 45-65yo (Dahnert).
  a. Clinically measured rheumatoid factor is IgG - F - RF are antibodies directed against the Fc portion of IgG. RF is currently measured in clinical practice as and IgM RF, although other immunoglobulin types, including IgG and IgA, have been described.
  b. Commonest 5th-7th decades - T - peak incidence during 4th to 8th decades (path notes). Peak age: 45-65yo (Dahnert).
  c. C spine involved in 50% - F - Cx spine involvement in RA is common (up to 90%) and is more sommon with long standing disease and multiple joint involvement. Significant subluxations will occur in about 32% (Wheeless’ textbook Ortho).
  d. Female to male ratio of 10:1 - F - F>M : 2-3:1 (Path notes). M:F 1:3 if <40yo, and M=F if >40yo.

Question 77

80. Which is true regarding EG?
    a. It is in the spectrum of Langerhans cell histiocytosis
    b. It is a neoplasm

Answer 77

80. Which is true regarding EG? (JS) answer : A

a. It is in the spectrum of Langerhans cell histiocytosis - T - LCH is a reactive, non-neoplastic proliferative disorder resulting from disturbances in immuno-regulation. 3 different clinicopathologic entities- Letterer-Siwe, Hand-Schuller-Christian and EG
b. It is a neoplasm - F - non-neoplastic