Oncology Flashcards

Question 1

Q

Approach to benign aggressive lesion

Answer

A

Comprehensive history
Comprehensive physical
Radiographs

Look for neocortex
Usually epiphyseal/metaphyseal
Usually lytic
DDx
- ABC
  - (Telangiectactic osteosarcoma) Include in DDx for ABC
- GCT
- CMF
- Osteoblastoma
- Chondroblastoma
  - If epiphyseal, DDx includes clear cell chondrosarcoma

MRI
CXR

Lung mets
- GCT
- Chondroblastoma

Biopsy
Treatment

Generally, extended intralesional curettage and bone grafting
- ***NOTE:
  - Augments include high speed burr, phenol, liquid nitrogen
En bloc resection and reconstruction
- If eroded through cortex

Followup

History and physical examination
GCT - limb and chest radiographs q3m x 2y, then q6m to 5y, then yearly to 10y

Question 2

Q

Approach to Osteosarcoma

Answer

A

Comprehensive history
Comprehensive physical
Radiographs

Ddx
- Osteosarcoma
- Ewing’s
- Infection
- EG
- Hematologic malignancy

Full length MRI
Bone scan
CT chest
Biopsy
* CT or US guided core needle biopsy OR open
Consult medical oncology

Prior to chemo:
- BW – LDH, ALP, CBC, LFTs, urea/Cr
- Echo
- Audiogram
  1. Neoadjuvant chemotherapy
Doxorubicin, methotrexate, cisplatin
10 week course preop

10.Re-stage

Radiographs
Full length MRI
Bone scan
CT chest

Surgery

Limb sparing surgery with wide margin resection and reconstruction
- Tumor prosthesis
- Intercalary allograft/autograft
- Rotationplasty
- APC
Amputation
- Pathological fracture
- Encasing neurovascular structures
- Poor response to chemo
  1. Adjuvant chemotherapy
Doxorubicin, methotrexate, cisplatin
?6 months

Followup (Surveillance)

History, physical, CXR, extremity x-ray
Every 3 months for 2 years, 6 months until year 5, then annually until year 10

Question 3

Q

Approach to Ewing’s Sarcoma

Answer

A

Comprehensive history
Comprehensive physical
Radiographs

Ddx
- Osteosarcoma
- Infection
- EG
- Hematologic malignancy

Full length MRI
Bone scan
CT chest
*Bone marrow biopsy
Biopsy
* CT or US guided core needle biopsy OR open
Consult medical oncology

Prior to chemo:
- BW – LDH, ALP, CBC, LFTs, urea/Cr
- Echo
- Audiogram

Neoadjuvant chemotherapy

*Doxorubicin, Vincristine, Cyclophosphamide, ifosfamide and etoposide
~10 week course (4-8 cycles)

Re-stage

Radiographs
Full length MRI
Bone scan
CT chest

Surgery

Limb sparing surgery with wide margin resection and reconstruction
- Tumor prosthesis
- Intercalary allograft/autograft
- Rotationplasty,
- APC
Amputation
- Pathological fracture
- Encasing neurovascular structures
- Poor response to chemo
- Lesions of foot or ankle
  1. Adjuvant chemotherapy
?6 months
14. *Radiation if inadequate surgical margins OR surgery would be too morbid or unresectable (pelvis, spine, etc)
15. Followup (Surveillance)
History, physical, CXR, extremity x-ray
Every 3 months for 2 years, 6 months until year 5, then annually until year 10

Question 4

Q

Approach to Soft Tissue Sarcoma

Answer

A

Comprehensive history
Comprehensive physical
(Radiographs)
MRI
CXR
CT chest
* If myxoid liposarcoma = CT chest/abdo/pelvis
Biopsy
* US guided core needle biopsy
Consult radiation oncology

Pre-operative
- Lower dose (~50Gy) over ~5 weeks with surgery ~4 weeks after completion
- Higher wound complication
Post-operative
- Higher dose (~66Gy)
- More fibrosis and joint contractures

Surgery
* Wide surgical resection (>1cm margins)
Followup

History, physical, CXR
Every 3 months for 1 year, q6months for 1 year, then annually for 10 years

Question 5

Q

Approach to isolated destructive bone lesion in an adult

Answer

A

Comprehensive history
Comprehensive physical
Radiographs

Ddx
- Mets
- Myeloma
- Lymphoma
- Primary bone tumor
- Infection

Bloodwork

CBC, Lytes, extended lytes, Cr, urea
ALP, LDH, PTH, LFTs
SPEP
ESR/CRP
PSA

Urine

Urinalysis
UPEP

Imaging

Full length radiographs
Bone scan
CT chest/abdo/pelvis
CT/MRI of lesion (full length bone involved)
Optional:
- Skeletal survey
- Thyroid US
- Mammography
  1. Biopsy
CT/US core needle biopsy OR open
8. Treatment of confirmed metastatic bone lesion
+/- preoperative IR embolization for RCC/thyroid mets
Construct providing immediate stability and protection of entire bone
- IM nail vs. plate
- Possible tumor prosthesis for joint involvement
- +/- cement augmentation for stability
Local control
- Surgical curettage/resection of bone segment
- Consult radiation oncology for postoperative radiation
Bisphosphonate
9. Followup

Question 6

Q

Radiographic assessment of a bone lesion should assess/describe the following factors?

Answer

A

Type of radiograph (eg. AP/lateral right knee)
Skeletally immature or mature
Site of the lesion

Epiphysis, metaphysis, diaphysis
Central, eccentric, cortical, periosteal

Geographic vs. nongeographic border
* Nongeographic = moth-eaten or permeative
Matrix

Osteoid
Chondroid (stippled, rings and arcs, flocculent)
Myxoid
Fibrous

Cortex involvement

Endosteal scalloping
Thinning
Expanded
Neocortex
Disrupted

Periosteal reaction

None
Continuous (cortical thickening)
Sunburst (hair-on-end)
Onion skin
Codman’s triangle

Soft tissue mass
Size and number of lesions

Question 7

Q

Pediatric aggressive malignant lesions

Answer

A

Ewing’s sarcoma
Osteosarcoma
Infection
Eosinophilic granuloma
Hematologic malignancy
Metastatic tumor (Wilm’s, Neuroblastoma)

Question 8

Q

Benign Aggressive bone tumour

Answer

A

ABC
- (Telangiectactic osteosarcoma) Include in DDx for ABC
GCT
CMF
Osteoblastoma
Chondroblastoma
- If epiphyseal, DDx includes clear cell chondrosarcoma

Question 9

Q

Lesions in the posterior elements of the spine

Answer

A

Osteoblastoma
Osteoid osteoma
Osteochondroma
ABC
Metastasis

Question 10

Q

Lesions in the epiphysis

Answer

A

Chondroblastoma
Clear cell chondrosarcoma
Geode
Infection
EG

Question 11

Q

Anterior tibial cortical thickening differential?

Answer

A

Stress fracture
Osteoid osteoma
Infection

Question 12

Q

What are the ‘small round blue cell’ tumours?

Answer

A

LEARN

Lymphoma
Ewings
Acute leukemia
Rhabdomyosarcoma
Neuroblastoma

Question 13

Q

What types of surgical margins can be considered?

[AAOS comprehensive review 2, 2014, pg. 487]

Answer

A

Intralesional
Marginal
Wide
Radical

Question 14

Q

Tumors treated with wide resection alone?

[AAOS comprehensive review 2, 2014]

Answer

A

Chondrosarcoma
Adamantinoma
Parosteal osteosarcoma
Chordoma

Question 15

Q

What are the most common bone tumours?

[Orthobullets][AAOS comprehensive review 2, 2014]

Answer

A

Most common malignancy of bone = metastasis
Most common malignancy of bone in children = intramedullary osteosarcoma
Most common primary bone malignancy = myeloma
Most common bone sarcoma = intramedullary osteosarcoma
Most common soft tissue sarcoma of hand/wrist = epitheliod sarcoma
Most common soft tissue sarcoma of foot = synovial sarcoma

Question 16

Q

What are complications of radiation treatment in skeletally immature patients?

Answer

A

Joint contractures
Fibrosis
Growth arrest (LLD)
Fracture
Secondary malignancy

Question 17

Q

What are the syndromes associated with the following tumors?

Question 18

Q

What are the biopsy principles?

Answer

A

Incision in line with planned resection incision
* Longitudinal in extremities
Go through muscle compartments (not around)
Meticulous hemostasis

Prevents hematoma and tumor spread
Drain if needed, avoid if possible, place distal in line with incision

Do not undermine or raise flaps
Avoid neurovascular structures and joints
Biopsy soft tissue mass if present
* If not, enter bone through weakest cortex, drill oval/round window if needed
Send frozen section for lesional tissue

Should also always send fresh tissue
- Lymphoma of bone needs fresh tissue for flow cytometry
Consider sending for C&S if infection on differential

Water tight closure

***NOTE: if biopsy bleeds do not extend incision

Manage bleed with gel foam, packing, cement or drain

Question 19

Q

What is the differential for an isolated destructive bone lesion in an adult?

Answer

A

Metastasis
Multiple myeloma
Lymphoma
Primary bone tumours

Chondrosarcoma
Malignant fibrous histiocytoma
Chordoma
Osteosarcoma

Benign lesions
* Giant cell tumour
Non-neoplastic

HyperPTH
Osteomyelitis
Gorham vanishing bone disease
- Progressive bone loss (osteolysis) and the overgrowth (proliferation) of lymphatic vessels

Question 20

Q

Workup for unknown primary?

Answer

A

Undertaken when an adult presents with a destructive bone lesion without a history of cancer

Must differentiate between metastatic disease and primary bone tumour
1. Bloodwork
CBC, Lytes, extended lytes, Cr, urea
ALP, LDH, PTH, LFTs
SPEP
ESR/CRP
PSA

Urine

Urinalysis
UPEP

Imaging

Full length radiographs
Bone scan
CT chest/abdo/pelvis
CT/MRI of lesion (full length bone involved)
Optional:
- Skeletal survey
- Thyroid US
- Mammography
  1. Biopsy

Question 21

Q

What primary tumors commonly metastasize to bone?

Answer

A

BLT KP

Breast
Lung
Thyroid
Kidney
Prostate

Question 22

Q

Consider preoperative (pre-open biopsy) embolization for which bone lesions?

Answer

A

Renal cell carcinoma mets
Thyroid carcinoma mets

Question 23

Q

What malignant lesions are commonly cold on bone scan?

Answer

A

Multiple myeloma
Thyroid mets
Renal mets

Question 24

Q

What metastatic cancers are sensitive to radiation and which are resistant?

Answer

A

Radiosensitive

Lung
Breast
Prostate
Lymphoma
Myeloma

Radioresistant (think cold bone scan)

RCC
Thyroid carcinoma
Melanoma
GI adenocarcinoma

Question 25

Q

What nonoperative management can benefit lytic destructive lesion in adult?

Answer

A

Bisphosphonate

Question 26

Q

What is Mirel’s Classification/Score?

Answer

A

The goal is to predict impending fractures and prophylactically fix in an elective setting
* Avoids urgent hospitalisation and severe pain associated with pathological fractures and allows for medical optimization to minimize the risk of surgery
Considers

Site of lesion (UE, LE, trochanteric region)
Nature of lesion (blastic, mixed, lytic)
Size of lesion (<1/3, 1/3-2/3, >2/3 of cortex)
Pain (mild, moderate, functional)
3. According to Mirels’ recommendations:
Score >8 - prophylactic fixation is indicated
Score <8 - lesion can be managed with radiation or drugs
Score = 8 - clinical dilemma
- Probability of fracture is 15% and clinician should use clinical judgement

Sensitivity = 91%, specificity = 35%
* Specificity of 35% may lead to false positives and unnecessary procedures

Question 27

Q

What are the benefits of prophylactic fixation of a metastatic bone lesion?

[AAOS comprehensive review 2, 2014, pg. 487]

Answer

A

Avoids urgent hospitalization
Decreased perioperative pain
Allows for medical optimization
Technically easier surgery
Shorter OR time
Faster recovery/decreased length of stay
Allows for coordination with medical oncology

Question 28

Q

What are the surgical goals and options for the management of metastatic bone disease?

[JBJS 2009; 91(6): 1503]

Answer

A

Immediate stability, protect the entire bone, reduce pain and increase function
Local tumor control
* Radiation or local surgical curettage/resection of bone segment
Long bones

Closed IM nailing preferred
- Without cement if minimal bone destruction
- With cement if significant bone destruction
Plates if nonWB bone (eg. humerus) or lesion too proximal or distal for nail
Tumour prosthesis if joint involvement

Acetabulum
* Harrington technique – threaded pins in ilium as rebar support for cemented acetabular component

Question 29

Q

What is the management of massive bleeding during local tumor control (eg. RCC)?

[CORF]

Answer

A

Remove tumor as fast as possible
Be prepared for blood loss – have cement available
Notify anaesthesia
Call for blood products

Question 30

Q

When can a solitary destructive bony lesion be nailed?

Answer

A

Known metastatic malignancy
Frozen section sent at time of surgery confirming ‘carcinoma’

Question 31

Q

What is the management of hypercalcemia of malignancy?

[Am Fam Physician. 2003 May 1;67(9):1959-1966.]

Answer

A

Recognize symptoms

“Stones, bones, abdominal moans, and psychic groans”
Confusion, malaise, fatigue*
Abdominal pain, nausea*

ECG
Hydration

Insert Foley
Bolus IV normal saline 1-2L, then run freely to achieve urine output of 150-200cc/h

Loop diuretic (eg. Lasix)
* Start once intravascular volume restored
Medicine consult

Bisphosphonate
Calcitonin
Dialysis

Question 32

Q

What type of resection is required when a bone sarcoma involves a joint?

Answer

A

Extra-articular resection

E.g. knee involvement is performed either by en-block resection or resection with preservation of the extensor mechanism (splitting the patella and detaching suprapatellar pouch from quads tendon and fat pad from patellar tendon)

Question 33

Q

Hemipelvectomy:

What is the difference between an internal vs. external hemipelvectomy?

What 3 structures must be considered when deciding between internal and external hemipelvectomy?

What are flap closure options for hemipelvectomy?

Answer

A

Internal vs External

Internal – limb-sparing surgery
- Hemipelvis resected, leg preserved
External – hindquarter amputatio
- Hemipelvis and leg amputated

Important structures

Sciatic nerve
Femoral neurovascular bundle
Hip joint
***General rule = should two of these structures require resection to obtain an adequate margin, then external hemipelvectomy should be performed
3. Flap closure options:
Anterior flap – femoral blood supply
- Indicated if tumor involves buttock or internal iliac vessels
Posterior flap (classic) – internal iliac blood supply
- Indicated if tumor involves external iliac or femoral vessels
Free flap

Question 34

Q

Osteoid Osteoma

Classification

Age

Presentation

Location

Imaging

Treatment

DDx

Answer

A

Classification - Benign active
Age = 5-30
Presentation:

Classically night pain relieved with ASA or NSAIDs
May cause a painful scoliosis
- If so lesion located at the centre of the concavity of the curve

Location:
* Most common = proximal femur
Imaging:
* Radiographs = round, well-circumscribed intracortical lesion with radiolucent nidus, surrounding reactive sclerosis, benign periosteal reaction
- Nidus is always less than 1.5cm (sclerosis may extend beyond)
  * CT (thin slice) = identifies radiolucent nidus (often key to diagnosis)
  * MRI = also can show nidus as well as adjacent edema (not needed routinely)
Treatment

Expectant observation and NSAIDs
- Pain is self-limiting treated with NSAIDs, burns out on average in 3 years
Radiofrequency ablation (RFA)
- Failure of NSAIDs
- Contraindicated if adjacent to nerve roots or spinal cord
- Recurrence = 10-15%
Surgical resection/currettage
- Indicated if close to spinal cord/nerve root/skin, painful scoliosis, digits
  1. Differential for cortical osteoid osteoma
Cortical bone abscess
Stress fracture (linear radiolucency)
Intracortical osteosarcoma
Osteoblastoma (>2cm)

Differential for an intramedullary osteoid osteoma

Brodies abscess
Osteoblastoma
Bone island

Question 35

Q

Osteoblastoma

Classification

Age

Presentation

Location

Imaging

Treatment

DDx

Answer

A

Classification - Benign aggressive
Age = 10-30
Presentation

Slow, progressive dull, aching pain
- Differs from osteoid osteoma in that it is less severe, not night pain, not relieved with ASA

Location

Most common = posterior elements of the spine
2/3 are cortically-based, 1/3 are medullary-based

Imaging

Radiographs = radiolucent nidus >2cm
- Surrounding reactive sclerosis
- Expansile with neocortex
CT = indicated to evaluate extent of lesion

Treatment

Currettage and bone grafting or en bloc resection
Not self limiting so observation not indicated

Differential diagnosis

Osteoid osteoma
Brodies abscess
ABC
Osteosarcoma

Question 36

Q

Bone Island

Classification

Presentation

Location

Imaging

Treatment

Assoc Conditions

Answer

A

Classification - Benign latent (?)
Presentation
* Incidental finding
Location

Most common = pelvis and proximal femur
Medullary cavity

Imaging

Radiographs = round focus of dense bone occasionally with radiating spiculus of bone
MRI = no surrounding edema

Treatment

None
Repeat radiographs if diagnosis is in doubt

Associated Conditions
* Osteopoikilosis = hereditary multiple bone islands

Question 37

Q

Enchondroma

Classificatino

Age

Presentation

Location

Imaging

Treatment

Assoc Conditions

DDx

Answer

A

Classification - Benign latent (cartilage)
Age = 20-50
Presentation

Asymptomatic, incidental finding most common
Pain may be associated with:
- Lesions in small bones of hands/feet
- Pathological fracture
- Malignant transformation (<1% Chondrosarcoma)

Location

Most common = hand
- Also feet, diaphysis and metaphysis of long bones
Medullary cavity

Imaging

Radiographs = rings and stippled calcifications within the medullary cavity
- Minimal endosteal erosion (<50%)
- Cortical expansion and thinning may be present in hands and feet (not in long bones)

Treatment

Observation
Intralesional currettage and bone grafting
- Indications:
  - Large lesion at risk of recurrent fracture
  - Radiographs suspicious for low-grade chondrosarcoma
  - Serial radiographs showing change in lesion

Associated Conditions

Ollier disease
- Spontaneous mutation
- Multiple enchondromas
- Associated with shortening and bowing deformities
- 25-30% chance of malignant degeneration to low grade chondrosarcoma
Maffucci syndrome
- Multiple enchondromas and soft-tissue angiomas
- Up to 100% chance of malignant degeneration to low grade chondrosarcoma
  1. DDx for solitary enchondroma
Bone infarct
Chondrosarcoma
Chondroblastoma (if affects end of bone)
GCT (if affects end of bone and no calcifications)

Question 38

Q

Periosteal Chondroma

Classification

Age

Presentation

Location

Imaging

Treatment

Answer

A

Classification: Benign active (?) (Cartilage)
Age = 10-30
Presentation
* Pain or incidental finding
Location
* Surface of long bones and hands
Imaging

Radiographs = surface lesion
- Saucerization of underlying cortex with rim of sclerosis
- Variable calcification

Treatment

Observation
Marginal exicision
- Symptomatic

Question 39

Q

Osteochondroma

Classification

Presentation

Imaging

Treatment

Assoc Conditions

Answer

A

Classification - Benign (Cartilage)
Presentation

Asymptomatic, palpable immobile mass
Pain if inflamed overlying bursa, fracture of stalk, nerve compression, malignant degeneration (higher risk in sessile form)

Imaging

Radiographs = Sessile or pedunculated
- Cortex of stalk continuous with adjacent bone
- Medullary canal continuous with stalk (“corticomedullary continuity”)
- Pedunculated grow away from joint

Treatment

Observation
- Asymptomatic
Marginal resection at base of stalk including cartilage cap (delay until skeletal maturity preferred)
- Indications = symptomatic, cosmetic, vascular or nerve compression
  1. Associated condition
Multiple Hereditary Exostosis
- Autosomal dominant mutation in EXT 1, EXT 2
  - EXT-1 has more serious disease manifestations
- Associated with:
  - Short stature
  - Metaphyseal widening
  - Primarily sessile lesions
  - Long bone deformities
  - Higher risk of malignant transformation (5-10% Chondrosarcoma)
Trevor’s disease
- Osteochondroma arising from epiphysis
  - Most commonly located in tarsals followed by knee

Question 40

Q

Chondroblastoma

Classification

Age

Presentation

Location

Imaging

Histology

Treatment

DDx

Answer

A

Classification - Benign Aggressive (Chondroid)
Age = <25 (80%)
Presentation

Progressive pain, limp, decreased ROM, tenderness
Benign pulmonary metastasis (<1%)

Location

Most common = knee (distal femur, proximal tibia)
- Also proximal humerus, proximal femur, calcaneus, flat bones
Epiphysis or apophysis, often with extension into the metaphysis

Imaging

Radiographs = well circumscribed lytic lesion with sclerotic rim
- Stippled calcification (25-40%)
- May have cortical expansion

Histology
* ‘Chicken Wire Calcifications’ surround chondroblasts
Treatment

Extended intralesional curretage with bone grafting
- Adjuvants include phenol or liquid nitrogen to reduce recurrence
Surgical resection of benign pulmonary metastasis when present

Differential diagnosis

Clear cell chondrosarcoma
Bone abscess
Osteonecrosis
Intraosseous ganglion
GCT
Osteoblastoma
Enchondroma

Question 41

Q

Chondromyxoid Fibroma

Classification

Age

Presentation

Location

Imaging

Histology

Treatment

DDx

Answer

A

Classification - Benign active (chondroid)
Age = 10-30
Presentation

Pain and mild swelling
May be incidental finding

Location

Most common = long bones of lower extremity and pelvis
- Also hands and feet
Metaphysis

Imaging

Radiographs = lytic, eccentric metaphyseal lesion
- Thinning and expansion of adjacent cortical bone
- Sharp sclerotic rim

Histology
* Stellate cells
Treatment
* Intralesional currettage and bone grafting
Differential diagnosis:

NOF
Fibrous dysplasia
ABC
Osteofibrous dysplasia (if in tibia)
GCT (if extends to epiphysis)

Question 42

Q

Nonossifying Fibroma (NOF)

Classification

Age

Presentation

Location

Imaging

Treatment

Assoc Conditions

Answer

A

Classification - Benign latent (fibrous)
Age = 5-15
* 30% of children with open physes have NOF
Presentation

Asymptomatic, incidental finding
Pathological fracture

Location

Most common = long bones of lower extremities
Cortically based, start in metaphysis and migrate to diaphysis

Imaging

Radiographs = eccentric, lytic, ‘bubbly’
- Cortically based lesion with sclerotic rim
- Cortex may be expanded and thinned
  - As patient reaches skeletal maturity the lesion ossifies and becomes sclerotic

Treatment

Observation
- Serial radiographs should be considered for larger lesions
Intralesional currettage and bone grafting
- If symptomatic and large lesion
Pathological fractures are treated as per fracture and allowed to heal
- Consider intralesional currettage and bone grafting if high risk of recurrence

Associated conditions

Familial multifocal
Neurofibromatosis
Jaffe-Campanacci syndrome

Question 43

Q

Fibrous Dysplasia

Classification

Age

Presentation

Location

Imaging

Histology

Treatment

Assoc Conditions

Answer

A

Classification - Benign active (fibrous)
Age = all ages (75% seen in patients younger than 30)
Presentation

Asymptomatic, incidental finding
Pathological or fatigue fractures resulting in pain

Location

Most common = proximal femur, rib, maxilla, tibia (can affect any bone)
Medullary cavity
Monostotic (single bone) or polyostotic (more than one bone)

Imaging

Radiographs = central, lytic lesion
- Often ground glass appearing in diaphysis/metaphysis
- Surrounding sclerotic rim
- May be expansile with cortical thinning
  - Bowing deformity in proximal femur (Shepherd’s crook) or tibia
  - Vertebral collapse and kyphoscoliosis

Histology

“Chinese letters” or “alphabet soup” appearance
- Immature fibrous tissue surrounding islands of woven bone

Treatment

Observation
- Asymptomatic
Bisphosphonate
- Indicated in symptomatic polyostotic fibrous dysplasia
Internal fixation with bone grafting
- Indications:
  - Pain
  - Impending/actual pathological fracture
  - Severe deformity
  - Neurological compromise (spine)
- Technique – IM nail preferred over plate
  - Do not use cancellous autograft as it turns into dysplastic woven bone
  - Use cortical allograft
Osteotomies
- Indication – coxa vara deformity (intertrochanteric osteotomy)
  1. Associated conditions
McCune-Albright syndrome
- Triad of polyostotic fibrous dysplasia, precocious puberty, café-au-lait spots (coast of Maine)
Mazabraud syndrome
- Polyostotic fibrous dysplasia and multiple intramuscular myxomas
Cranial deformities and blindness with craniofacial involvement

Question 44

Q

Osteofibrous Dysplasia

Classification

Age

Presentation

Location

Imaging

Treatment

Answer

A

Classification - Benign active (fibrous)
Age = <10
Presentation

Painless swelling over anterior border of tibia
Anterior or anterolateral tibial bowing
- Pseudoarthrosis in 10-30%

Location

Most common = anterior tibia
Cortically-based, usually diaphyseal

Imaging

Radiographs = eccentric, anterior tibia cortical lytic lesion surrounded by sclerosis
- No periosteal reaction

Treatment

Observation (avoid surgery if possible)
Bracing – if deformity present
Deformity correction
- Rarely needed, perform after skeletal maturity if significant deformity present

Question 45

Q

Desmoplastic Fibroma

Classification

Age

Presentation

Location

Imaging

Treatment

Answer

A

Classification - Benign aggressive (fibrous)
* Extremely rare
Age = 10-30
Presentation
* Pain, mass, swelling
Location

Any bone
Metaphysis

Imaging

Radiographs = lytic lesion central in the metaphysis with soap-bubbly/trabeculated appearance
- May appear aggressive

Treatment
* Wide surgical resection vs. intralesional currettage

Question 46

Q

Eosinophilic Granuloma

AKA Langerhans cell histiocytosis, histiocytosis X

Classification?

Age

Presentation

Location

Imaging

Histology

Treatment

Answer

A

Classification -
Age = <20
Presentation

Solitary disease (EG)
- Pain, swelling
Hand-Schuller-Christian disease
- Chronic, disseminated form with visceral involvement
- Triad = multiple lytic skull lesions, diabetes insipidus, exopthalmus
Letterer-Siwe disease
- Infantile, fatal

Location

Most common = skull, ribs, clavicle, scapula, vertebrae, long bones, pelvis
Can occur in any bone

Imaging

Radiographs = ‘the great mimicker’
- Diaphyseal lesions = classically punched out lytic lesions
  - Cortex may be thinned or destroyed
  - May have periosteal reaction (can be geographic or permeative)
- Vertebral plana, kyphosis
- Cranial lesions = multiple punched out lytic lesions
  1. Histology
Mixed inflammatory cell infiltrate
- Langerhans cells = indented nuclei (‘coffee bean’)
  - Stain with CD1a
  - On electron microscope = Birbeck granules (‘tennis racket’)
- Eosinophils = pink cytoplasm
- Giant cells are present
  1. Treatment
Observation – solitary lesions
Corticosteroid injections (intralesional) – solitary lesions
Low dose irradiation
- Reserved for lesions in the spine or lesions not amenable to injection or surgery
Bracing
- Prevents kyphosis in vertebra plana (90% effective)
Chemotherapy
- Reserved for Hand-Schuller-Christian disease
Intralesional currettage and bone grafting
- Risk of impending fracture or articular involvement

Question 47

Q

Unicameral Bone Cyst (UBC)

Classification

Age

Presentation

Location

Imaging

Treatment

Answer

A

Classification - Benign active (cystic)
Age = <20
Presentation
* Most common = pathologic fracture

4, Location

Most common = proximal humerus, proximal femur, ilium, calcaneus
Medullary cavity

Imaging

Radiographs = central, lytic, well-demarcated metaphyseal lesion
- Expansion and thinning of the cortex
- Expansion is no wider than the physis
- ‘Fallen Leaf Sign” – pathognomonic
  - Pathologic fracture where a cortical fragment falls into the base of the lesion
- Start adjacent to physis (active) then progress towards diaphysis (latent)
- Trabeculated appearance after multiple fractures
MRI = bright on T2, dark on T1

Treatment

Observation – asymptomatic lesions
Pathological fracture:
- Proximal humerus – nonop
- ~15% of lesions fill in with native bone after fracture
Intralesional injection of methylprednisolone
- Indicated for active lesions, may require multiple injections
Intralesional currettage, bone grafting and ORIF
- Indicated in proximal femur fractures at high risk of pathological fracture or re-fracture
- Symptomatic latent cysts that have not responded to injections

Question 48

Q

Aneurysmal Bone Cyst (ABC)

Classification

Age

Presentation

Location

Imaging

Histology

Treatment

Assoc Conditions

DDx

Answer

A

Classification - Benign aggressive (cystic)
Age = <20 (75%)
Presentation

Most common = pain, swelling
Pathological fracture
Neurological symptoms with spine involvement

Location

Most common = knee (distal femur, proximal tibia)
- Also pelvis, posterior elements of spine
Metaphysis, eccentric

Imaging

Radiographs = expansile, eccentric, lytic lesion with soap-bubbly appearance
- Neocortex
- Can expand wider than the width of the physis
MRI = fluid-fluid levels (separation of serum from blood products)

Histology

Blood-filled cysts without a true endothelial lining
Lining contains giant cells and spindle cells
“Snakes and blood”

Treatment

Extended intralesional currettage and bone grafting
- Consider adjuvants phenol and liquid nitrogen
- If pathological fracture, treat fracture nonoperative first then currettage (unless spontaneous resolution of ABC)

Associated conditions

Arises from other tumours 30% of cases
- GCT, chondroblastoma, CMF, NOF, osteoblastoma, FD
Telangiectactic osteosarcoma – radiographic and histological differential

Differential diagnosis

UBC
CMF
GCT
Telangiectatic osteosarcoma

Question 49

Q

Giant Cell Tumour

Classification

Age

Presentation

Location

Imaging

Histology

Treatment

Assoc Conditions

Answer

A

Classification - Benign aggressive
Age = 30-50
Presentation

Pain and swelling
Pathological fracture

Location

Most common = knee (distal femur, proximal tibia)
- Distal radius, proximal humerus, proximal femur, sacral ala, pelvis
- Vertebral body when spine involved
Metaphysis, epiphysis, apophysis
Eccentric

Imaging

Radiographs = eccentric, lytic lesion located in metaphysis/epiphysis
- Often extending to subchondral bone
- Expands bone
- Neocortex

6. Histology

Scattered giant cells on background of mononuclear stromal cells (neoplastic cells)
7. Treatment
Extensive intralesional currettage and bone grafting or cement
- Consider adjuvants phenol or liquid nitrogen
- 10-15% recurrence
  - Adjuvants (PMMA) decrease recurrence compared to bone graft
- If cement used WB can be immediate
En bloc resection and reconstruction
Denosumab (controversial)
- Assoc complications:
  - Increased recurrence, arthralgia, headache, nausea, fatigue, pain, anemia, hypercalcemia and osteonecrosis in jaw
Radiation
Lung metastasis (2%)
- Thoracotomy, radiation, chemo, or observation
- 10-15% die due to mets
  1. Associated conditions
Malignant transformation to high grade sarcoma (<1%)
Secondary ABC

Question 50

Q

What is the Enneking Classification of Malignant Bone Tumours?

Answer

A

Stage IA = low grade, intracompartmental
Stage IB = low grade, extracompartmental
Stage IIA = high grade, intracompartmental
Stage IIB = high grade, extracompartmental
Stage III = metastatic disease

A = confined to bone, no soft tissue involvement

B = penetration of the cortex with a soft tissue mass

Question 51

Q

Intramedullary Osteosarcoma

Classification

Age

Presentation

Location

Imaging

Histology

Staging

Treatment

Prognosis

Assoc Conditions

Answer

A

Classification - Malignant
Age = most common 2nd decade (late peak in 6th decade)
Presentation

Constant pain (day/night), unrelieved by analgesics
Swelling, decreased ROM, limp, weakness
Pathological fracture (10%)

Location

Most common = knee (distal femur, proximal tibia)
- Also proximal humerus, pelvis, proximal femur
Typically, medullary cavity

Imaging

Radiographs = mixed blastic and lytic non-geographic lesion
- Sun-burst periosteal reaction
- Codman’s triangle
- Soft-tissue mass
MRI full-length bone involved = assess for skip lesions, neurovascular involvement, soft tissue mass
Bone scan = primary lesion very hot
- Evaluate for skip lesions
CT chest = order at presentation and assess for lung mets

Histology
* ‘Lacelike pattern’ of osteoid formed by malignant cells (atypia, abnormal mitotic figures, high nuclear to cytoplasmic ratio)
Staging

Enneking
- Most common = Stage IIB (high grade, extracompartmental, no metastasis)

Treatment

Neoadjuvant chemotherapy
Restage (MRI local, CT chest, bone scan, radiographs)
Surgery
- •Limb-sparing surgery with wide-margin resection and reconstruction (preferred)
  - Reconstructive options include tumour prosthesis, intercalary allograft, APC, rotationplasty
- Amputation
  - Indications:
    - Pathological fracture
    - Encasing neurovascular bundle
    - Poor response to chemotherapy
Adjuvant chemotherapy
9. Prognosis
70% 5 year survival for localized osteosarcoma in an extremity
- 25% 5 year survival for localized pelvic osteosarcoma
Poor prognostic factors
- Advanced tumour stage (most important)
  - Metastatic disease is poor prognostic factor
  - Most common site = lung (61%), bone (16%)
- Response to neoadjuvant chemotherapy
  - >90% tumour necrosis associated with increased survival
- Skip lesions
  - Occur in 10%, similar prognosis as lung metastasis
- Inadequate surgical margins
- Vascular involvement
- Elevated LDH, ALP
- Expression of VEGF, P-glycoprotein
- Expression of multi-drug resistance (MDR)
- Axial/pelvic involvement
  1. Associated conditions
Retinoblastoma tumour suppressor gene (RB1) carriers
Paget disease
Prior radiation
Rothmund-Thomson syndrome

Question 52

Q

Parosteal Osteosarcoma

Classification

Age

Presentation

Location

Imaging

Treatment

DDx

Answer

A

Classification - Malignant
Age = 20-45
Presentation

Painless mass of long duration
May have limited joint ROM, limp, pain

Location

Most common = posterior distal femur (75%)
- Also proximal tibia, proximal humerus
Surface of metaphysis

Imaging

Radiographs = dense/ossified, lobulated mass arising from the cortex
MRI full length bone = assess for skip lesions, soft tissue involvement, marrow involvement
Bone scan = lesion will be hot
- Assess for skip lesions
CT chest = assess for lung mets

Treatment

Wide local surgical resection
No chemo or radiation

Differential diagnosis

Parosteal osteoma
Melorheostosis
Sessile osteochondroma
Fracture callus
Myositis ossificans

Question 53

Q

Periosteal Osteosarcoma

Classification

Age

Presentation

Location

Imaging

Treatment

Answer

A

Classification - Malignant
* Extremely rare
Age = 15-25 ‘
Presentation
* Pain
Location

Most common = femoral or tibial diaphysis
Cortical/periosteal (no medullary canal involvement)

Imaging

Radiographs = sunburst periosteal reaction
- Underlying cortex may be saucerized (no medullary involvement)
CT chest = assess for lung mets
Bone scan = hot

Treatment

Same as intramedullary osteosarcoma
- Neoadjuvant Chemo
- Restage
- Wide margin resection
- Adjuvant Chemo

Question 54

Q

Telangiectatic Osteosarcoma

Classification

Age

Presentation

Location

Imaging

Histology

Treatment

Answer

A

Classification - Malignant
* Rare
Age, presentation = similar to intramedullary osteosarcoma
* Most common 2nd decade (late peak in 6th decade)

Constant pain (day/night), unrelieved by analgesics
Swelling, decreased ROM, limp, weakness
Pathological fracture (10%)

Location
* Proximal humerus, proximal femur, distal femur, proximal tibia
Imaging

Radiographs = purely lytic lesion
- Expansile, occasionally obliterates cortex
MRI = fluid-fluid levels, extensive edema

Histology

Differentiates from ABC
Gross = “bag of blood”
Atypical mitosis

Treatment

Same as intramedullary osteosarcoma
- Neoadjuvant Chemo
- Restage
- Wide margin resection
- Adjuvant Chemo

Question 55

Q

Secondary Osteosarcoma

Classification

Arises from

Prognosis

Answer

A

Classification - Malignant
Arises from:

Pagets
Fibrous dysplasia
Bone infarct
Chronic osteomyelitis
Osteogenesis imperfecta
Irradiation

Prognosis
* Very poor (as per CORR)

Question 56

Q

Undifferentiated Pleomorphic Sarcoma of Bone

AKA Malignant Fibrous Histiocytoma

Classification

Age

Presentation

Location

Imaging

Histology

Treatment

Answer

A

Classification - Malignant
Age = 20-80 (most common >40)
Presentation

Pain
Swelling, limp, decreased ROM
Pathologic fracture

Location

Distal femur, proximal tibia, proximal humerus
Metaphysis

Imaging

Radiographs = lytic lesions, often with cortical destruction and soft tissue mass
- Variable periosteal reaction
MRI = characterize lesion

Histology
* Spindle cells arranged in herringbone pattern
Treatment
* Similar to intramedullary osteosarcoma
- Neoadjuvant Chemo
- Restage
- Wide margin resection
- Adjuvant Chemo

Question 57

Q

Chondrosarcoma

Classification

Age

Presentation

Location

Imaging

Histology

Treatment

Assoc Conditions

Subtypes

Prognosis

Answer

A

Classification - Malignant
Age = 40-75
Presentation

Pain of prolonged duration
Slow growing firm mass
Pathological fractures

Location
* Most common = pelvis, proximal femur, scapula
Imaging

Radiographs
- Low grade = similar appearance to enchondroma
- High grade = cortical destruction and soft tissue mass
- Dedifferentiated = low grade lesion with superimposed high grade destructive area
MRI = assess for cortical destruction, marrow involvement, soft tissue involvement

Histology
* Low grade = bland appearance, few mitotic figures
* High grade = hypercellular cartilaginous lesion with atypical cells that permeate the bone trabeculae
Treatment

Intralesional currettage or wide resection = grade I
Wide surgical resection = grade II, III, dedifferentated and pelvic
***NOTE – chemotherapy and radiation are generally not effective

Associated conditions

Ollier’s
Mutliple hereditary exostosis
Osteochondroma
Enchondroma
Maffucci’s

Subtypes

Clear cell chondrosarcoma
- Epiphysis
- Confused with chondroblastoma
- Histology shows extensive clear cytoplasm
- Treatment is wide surgical resection
Mesenchymal chondrosarcoma

Prognosis

Secondary chondrosarcoma is better than primary
- Result is low grade chondrosarcoma
Dedifferentiated chondrosarcoma is the worst

Question 58

Q

Ewing Sarcoma

Classification

Age

Presentation

Location

Imaging

Histology

Genetics

Bone Marrow Biopsy

Treatment

Prognosis

Answer

A

Classification - Malignant
Age = 5-25
* Median age 15, >50% adolescents
Presentation

Pain
Often fever (20-28% - mistaken for infection)
Swelling, limp, decreased ROM
Palpable mass (34%)
Pathologic fracture (15%)
Delayed presentation/diagnosis common

Location

Pelvis, distal femur, proximal tibia, diaphysis of femur, proximal humerus
- Presents equally in flat and long bones
Diaphysis

Imaging

Radiographs = ill-defined, motheaten, permeative lytic bone destruction
- Periosteal reaction (onion skin or sunburst)
MRI = assess for soft tissue and marrow involvement
- Soft tissue component in 80%
Bone scan = hot
CT chest = assess for lung mets

Histology

Small round blue cells
Immunohistochemical staining positive for CD99 (95%), MIC-2

Genetics

t(11:22) [11:22 chromosomal translocation]
- Spontaneous translocation
- Produces EWS/FLI1 identified by PCR

Bone Marrow Biopsy
* Done because Ewing’s sarcoma can metastasize via the marrow
Treatment

Neoadjuvant chemotherapy (4-8 cycles)
Limb-sparing surgery with wide-margin resection and reconstruction (preferred)
- Consider amputation for:
  - Extremely large tumours involving NV structures
  - Unmanageable or displaced pathologic fracture
  - Lesions in the foot or ankle
Adjuvant chemo
Radiation (instead of surgery) for inoperable or metastatic disease
Adjuvant radiation
- Reserved for positive margins

Prognosis

80% 5 year survival for localized extremity
- 63% 10y survival
39% 5 year survival for metastasis
- 32% 10y survival
- Most commonly to lung and bone
Poor prognostic factors
- Metastatic disease (most important)
  - Especially nonpulmonary mets and distant mets
- Large tumour (>8cm, >100-200mL)
- Pelvic tumour
- Chemotherapy response (<90% necrosis)
- Older age (>14)
- Male (More common than female 1.5:1)
- Elevated LDH (>200)
- Relapse within 2y

Question 59

Q

Chordoma

Classification

Age

Presentation

Location

Imaging

Histology

Treatment

DDx

Answer

A

Classification - Malignant
Age = >40
Presentation

Insidious onset of low back or sacral pain
Bowel/bladder symptoms
50% palpable on rectal exam
Motor/sensory deficits rare (occur below S1)

Location

Sacrococcygeal region (50%)
- Spheno-occipital region (35%)
- Spine (15%)
Central, always has an anterior component
Metastasizes late (lung)

Imaging

Radiographs = difficult to assess due to overlying bowel gas
CT = midline bone destruction with soft tissue mass
- Calcifications may be present in soft tissue
MRI = lesion bright on T2

Histology

Transrectal biopsy contraindicated
Physaliferous cell (signature cell) contains vacuoles and appears bubbly
Keratin positive (differentiated from chondrosarcoma)

Treatment

Wide surgical resection
Radiation
- Reserved for inoperable tumours, positive margins, local recurrence

Differential diagnosis

Chondrosarcoma
Plasmacytoma
Metastasis
Osteomyelitis
Lymphoma

Question 60

Q

Adamantinoma

Classification

Age

Presentation

Location

Imaging

Histology

Genetics

Treatment

DDx

Answer

A

Classification - Malignant
Age = 20-40
Presentation

Pain and tenderness to anterior tibial border
Occasional tibial deformity or mass
History of preceding trauma common
4. Location
Most common = tibial diaphysis (90%)
Intracortical or intramedullary

Imaging

Radiographs = multiple well circumscribed lucent defects (soap-bubbly appearance)
No periosteal reaction

Histology
* Nests of epithelial cells in a benign fibrous stroma
Genetics
* Controversial whether evolves from osteofibrous dysplasia
Treatment

Wide margin surgical resection
- Reconstruction often with intercalary allograft
***Note – late mets to lung, bones, lymph nodes
- Requires long term followup

Differential diagnosis

Osteofibrous dysplasia
Fibrous dysplasia
NOF
Osteomyelitis

Question 61

Q

What are the general treatments for malignant bone tumours?

[3x3 table]

Question 62

Q

Multiple Myeloma

Classification

Age

Presentation

Location

Imaging

Labs

Histology

Treatment

Answer

A

Classification - Systemic (Marrow)
Age = >40
Presentation

Bone pain
Pathologic fractures
Cord compression
Recurrent infections

Location
* Most common = skull, spine, long bones
Imaging

Radiographs = multiple, punched out lytic lesions throughout skeleton
- No surrounding sclerosis
- Skeletal survey to look for additional lesions (bone scan cold)

Labs

SPEP, UPEP
Anemia, hypercalcemia, elevated creatinine, elevated ESR
- “CRAB”
  - Calcium high
  - Renal insufficiency
  - Anemia
  - Bone lesions

Histology

Plasma cells with eccentric nuclei
- Chromatin arranged in ‘clockface’
Immunohistochemistry = CD38+

Treatment

Chemotherapy (mainstay)
Stem cell transplant - not curative but increases survival
Bisphosphonates – decreases number of bone lesions, bone pain and lowers serum calcium
Surgical stabilization – pathological or impending fractures
- Treatment similar to metastatic disease
  - IM devices preferred
  - Protect full length of bone

Question 63

Q

Solitary Plasmacytoma

Answer

A

Plasma cell tumour in a single skeletal location
Progresses to multiple myeloma in 50% of cases
Negative SPEP/UPEP/bone marrow aspirate

Treatment

Radiation alone

Question 64

Q

Lymphoma

Classification

Age

Presentation

Location

Imaging

Histology

Treatment

Prognosis

Answer

A

Classification - Systemic (marrow)
Age = 35-55
Presentation

B symptoms = fever, weightloss, night sweats
Constant pain unrelieved with rest
Large tender, warm soft tissue mass
Pathologic fracture (25%)
4. Location
Most common = femur, spine, pelvis, ribs
5. Imaging
Radiographs = lytic, permeative lesions
- Often subtle bone destruction
- Soft tissue mass
- Multiple sites is common
- Ivory vertebrae
CT chest, abdo, pelvis = required for staging
MRI = extensive marrow involvement with soft tissue mass
PET scan = useful for staging and followup

Histology

Small round blue cell
Immunohistochemical staining = CD20+, CD45+

Treatment

Chemotherapy
Radiation
- Reserved for persistent disease
Surgery
- Only for pathological fractures

Prognosis
* 70% 5 year survival for disseminated disease

Answer 63

A

Classification - Benign (fat)
Age = 40-60
Presentation

Superficial lipoma – soft, painless, mobile mass
Deep lipoma – usually intramuscular, fixed, painless

Location

Superficial
- Upper back, shoulders, arms, buttocks, proximal thigh
Deep
- Thigh, shoulder, calf

Imaging

XR
- Radiulucent area within radiodense skeletal muscle
MRI
- Isointense with fat on all sequences
- T1 = bright
- T2 = intermediate
- Fat suppressed = suppresses

Histology
* Mature fat cells
Treatment

Observation
Marginal resection
- Indicated when symptomatic, growing rapidly

Answer 64

A

ALT vs WDL

Tumours with identical histology but differ in anatomic location and clinical outcomes
Precancerous
- Risk of malignant transformation depends on location and lesional duration

ALT

Location
- Extremity based or superficial trunk
  - Most common = thigh
- Deep to fascia
  - ~25% of deep lipomatous masses are ALT
Population
- Middle age, peak 50-60s
- M=F
Presentation
- Deep, large, painless, enlarging mass
Imaging
- MRI
  - Similar to lipomas (isointense to fat)
    - Differentiated by:
      - Deep to fascia
      - Larger (>10cm)
      - Thick fibrous septae (>2cm)
      - Post-gad enhancement
Histology
- In contrast to lipoma:
  - Pleomorphism
  - Nuclear atypia
  - Hyperchromatic stromal cells
Genetics
- MDM2 amplification (distinguishes from lipoma)
- CDK4 also amplified
Treatment
- Marginal excision
  - Wide excision decreases local recurrence but may be overly morbid for benign tumour
  - Adjuvant therapies not beneficial
Prognosis
- 100% survival
- 10% local recurrence (range 8-50%)
  - Avg 6-8y after surgical excision
  - 52% re-recurrence
- 0-5% risk of malignant dedifferentiation

WDL

=ALTs in anatomical locations not amenable to complete surgical resection
Location
- Retroperitoneum
  - 50% of lipomatous masses are WDLs and 45% are dedifferentiated liposarcomas
- Mediastinum
- Paratesticular
Presentation
- Larger than ALTs prior to symptoms/diagnosis
- Pain, neuro symptoms, GI bleeding possible
Imaging
- CT C/A/P
  - Required for retroperitoneal masses for planning and staging
Treatment
- Wide surgical excision
  - ~50% of patients require organ removal to achieve en bloc resection
- Debulking surgeries for recurrent retroperitoneal tumours have a role in prolonging survival
Prognosis
- Mortality rate >80%
  - Avg 6-11y to death
- Lack metastatic potential but incurable
- 10-20% risk of malignant dedifferentiation

Answer 65

A

Classification - Benign (vascular)
Age = <30
* Most common soft tissue mass in kids
Presentation
* Pain
Location
* Most common = lower extremities
Imaging

Radiographs = phleboliths or calcifications
- Adjacent bony erosion may be present
US = helps to differentiate type of lesion
MRI = increased signal intensity on T1 and T2
- “Bag of worms”

Treatment

Observation, NSAIDs, compression stockings
- Most lesions
IR embolization or sclerotherapy
- Reserved for large, painful lesions failing non-op treatment

Answer 66

A

Classification - Benign (nerve)
* Benign encapsulated tumor on surface of peripheral nerves composed of Schwann cells
Age = 20-50
Presentation

Usually asymptomatic
Pain associated with stretch or activity
Positive tinel sign

Location
* Flexor surfaces of extremities, pelvis
Imaging

MRI
- T1 = low signal
- T2 = high signal
  - Target sign
    - Low signal intensity surrounded by high intensity on T2
- Enhances with gadolinium
- Nerve may be seen entering and exiting the schwannoma
- ‘Split fat sign’
  - Fine fat deposition around the lesion and is usually seen as a tapered rim of fat signal adjacent to the proximal and distal ends of the lesion on T1-weighted coronal or axial images
  - Split fat is produced as a mass grows and normal intermuscular fat is displaced and effaced around the lesion

Histology

Verocay body – pathognomonic
- Two rows of aligned nuclei in a palisading formation

Treatment

Observation – asymptomatic lesions
Marginal excision with nerve fibre preservation – symptomatic

Answer 67

A

Classification - Benign (Reactive/Fibrous)
Age = 20-40
Presentation

Rapidly enlarging mass over 1-2 weeks (usally 1-2cm in size)
Painful in ~50%

Location
* Volar forearm, back, chest, head, neck
Imaging

MRI = nodularity, usually small
- Extension along fascial planes
- Enhances with gadolinium

Treatment
* Marginal resection

Answer 68

A

Classification - Benign (Mesechymal/Mucoid)
Age = 40-70
Presentation
* Painless mass (20% painful)
Location

Most common = thigh, buttock, shoulder, upper arm
Often close to neurovascular structures

Imaging

MRI = homogenous
- T2 = high signal
- T1 = low signal
- Within muscle groups

Histology

Minimal cellularity, no atypia
Cells suspended in abundant mucoid material

Treatment
* Marginal excision
Associated conditions

Mazabraud syndrome
- Multiple intramuscular myxomas in same general area as fibrous dysplasia

Answer 69

A

Classification - Benign (Fibrous)
* Locally invasive
Age = 15-40
Presentation

Painless mass
Hard, fixed and deep

Location

>50% are extra-abdominal = shoulder, chest, back, thigh
<50% are intra-abdominal = pelvis, mesentery

Imaging

MRI = T1 - low signal
- T2 = low-medium signal
- Infiltrative within muscle
- Usually 5-10cm in size
- Enhances with gadolinium

Histology

Bland fibroblasts with abundant collagen
No tumour capsule, often infiltrates into adjacent tissue

Treatment

Wide surgical resection
- Indicated if resectable
- Adjuvant radiation (high risk of recurrence)
Chemotherapy/tamoxifen
- Reserved for inoperable lesions

Associated conditions

Dupuytrens
Ledderhose disease (plantar fibromatoses)
Gardener syndrome
Familial adenomatous polyposis

Answer 70

A

Classification - Benign (Synovial)
Age = 30-50
Presentation

Pain, clicking, decreased ROM
Warmth, erythema, tenderness depending on joint
Slow progression of symptoms

Location

Most common = hip and knee
- Also shoulder and elbow

Imaging

Radiographs = variable depending on stage (not visible initially until calcify)
- Stippled calcification
MRI = lobular appearance

Histology

Gross = hundreds of osteocartilaginous loose bodies
Nodules are hyaline cartilage
- Chondrocytes have mild atypia

Treatment

Observation = Mild symptoms
Open or arthroscopic synovectomy = symptomatic
- May help prevent degenerative changes

Answer 71

A

Classification - Benign (synovial)
Age = 30-50
Presentation

Recurrent atraumatic hemarthrosis = hallmark
Diffuse form = pain, swelling, effusion, erythema, decreased ROM
Focal form = mechanical symptoms
Extra-articular form
- Giant cell tumour of tendon sheath
- = small, painless, superficial soft-tissue nodule

Location

Most common = knee (80%)
- Also hip, shoulder, ankle
Extra-articular form = giant cell tumour of tendon sheath
- Most common = hand/wrist

Imaging

Radiographs = may show cystic erosions on either side of joint with sclerosis
MRI = T1 and T2 - low signal intensity
- “Blooming artifact”
  - Signal loss on gradient echo sequences
- May show extra-articular extension

Histology

Gross = frond-like papillary projections
Mononuclear stromal cell infiltrate within the synovium
Hemosiderin-laden macrophages and multinucleated giant cells

Treatment

Arthroscopic and open synovectomy
- Indicated in symptomatic disease
Marginal excision
- Indicated in giant cell tumour of tendon sheath
TKA
- Indicated in advanced disease with secondary degeneration
Radiation
- Reserved for multiple recurrences

Answer 72

A

Classification - Benign (reactive)
Age = 15-35
Presentation

Pain, tenderness, swelling, decreased ROM after injury
- Followed by mass increasing in size over several months then growth stops and becomes firm

Location
* Most common = quadriceps, brachialis, gluteal
Imaging

Radiographs = initially, irregular, fluffy densities in the soft tissue
- Followed by peripheral mineralization and radiolucent centre
MRI = rim enhancement with gadolinium seen within first 3 weeks
CT = defines ossified lesion, looks like an egg-shell

Histology

Periphery = mature lamellar bone
Intermediate = poorly defined trabeculae with osteoblasts, fibroblasts and mitoses
Centre = immature, loose, fibrous tissue

Treatment

Observation
- Self limited process
- Size decreases after 1 year
Surgical excision
- Indicated only after mature (~6-12 months) and symptomatic

Answer 73

A

Classification - Malignant
* Hetergenous group of >50 types which behave in a similar fashion according to their size, location and grade
Age = >15 (80%)
Presentation

Painless enlarging mass
Nontender, firm, well-circumscribed
Constitutional symptoms and lymphadenopathy are uncommon

Location

Most common = extremities (60%)
Mets = most commonly lung

Imaging

Radiographs = generally nonspecific and nondiagnostic
MRI = enhance with gadolinium, usually respect fascial boundaries
CXR and CT chest = required for staging
CT chest/abdo/pelvis and Bone scan = for myxoid liposarcoma

Histology

Core needle biopsy required for indeterminate lesions
- Indetermine lesion = MRI cannot diagnose
- Determinate lesion = MRI diagnostic
  - Includes lipomas, hemangiomas, ganglion and synovial cysts, myositis ossificans, and PVNS
Grow in a centripital fashion surrounded by a pseudocapsule
- ‘Pushing tumor’ rather than ‘infiltrating tumor’
Appearance depends on type of sarcoma
7. Staging
AJCC (American Joint Committee on Cancer)
- Primary tumour (T)
  - TX – primary tumour cannot be assessed
  - T0 – no evidence of primary tumour
  - T1 - <5cm
    - T1a – superficial
    - T1b – deep
  - T2 - >5cm
    - T2a – superficial
    - T2b – deep
- Regional lymph nodes (N)
  - NX – cannot be assessed
  - N0 – no lymph node mets
  - N1 – lymph node mets
- Distant metastasis (M)
  - M0 – no distant mets
  - M1 – distant mets
- Histological grade (G)
  - G1 – well differentiated
  - G2 – moderately well differentiated
  - G3 – poorly differentiated
  - G4 – dedifferentiated
    8. Treatment
Wide surgical resection with cuff of normal tissue (>1cm)
Radiation
- Pre-operative – lower dose (~50Gy) over ~5 weeks with surgery ~4 weeks after completion
  - Higher wound complication (35% vs. 17%)
- Post-operative – higher dose (~66Gy)
  - More fibrosis and joint contractures
Chemotherapy
- Reserved for high grade, large tumours and mets
- 3 soft tissue sarcomas are chemo sensitive:
  - Embryonal rhabdomyosarcoma
  - Ewing’s soft tissue sarcoma of bone
  - (synovial sarcoma)
Surgical resection of lung mets
9. Prognosis
Low grade = 90% 5 year survival
High grade = 50% 5 year survival
Metastasis = 15% 5 year survival
Poor prognostic factors:
- Masses >5cm
- Masses deep to fascia
- Histologic high-grade
- Malignant tumor ulceration
- Radiation-induced STS
- Bony invasion
- Older patient age
- Lymph node involvement and mets
- Positive margins
  - Risk factor for local recurrence but not shown to affect survival

Answer 74

A

SCARE

Synovial sarcoma
Clear cell sarcoma
Angiosarcoma
Rhabdomyosarcoma
Epitheloid sarcoma

Answer 75

A

Classification - Malignant (fibrogenic)
* Previously MFH - Malignant Fibrous Histiocytoma
Age - 30-80
* Most common soft tissue sarcoma in adults 55-80
Presentation
* Most common = slow growing, painless mass
- May present with fever
  * May have history of trauma that draws attention to the mass
  * Painless soft tissue mass may be palpable

Lack of ecchymosis suggests an encapsulated mass
- Differentiates from hematoma, which typically presents with ecchymosis after trauma
Neurovascular
- Mass effect may cause neurovascular symptoms

Location
* Lower > upper extremities > retroperitoneum
Imaging

MRI = T1 - low signal intensity (isointense with muscle)
- T2 - high signal intensity

Histology

Gross
- Nodular, gray-white
3 subtypes
- Pleomorphic (80-85%)
- Giant cell (10%)
- Inflammatory (<10%)
Spindled, histiocytic, and multinucleated eosinophilic giant cells
Cells arranged in storiform (cartwheel) pattern arranged around small vessels
Atypia and mitoses present

Treatment

Wide surgical resection & radiation therapy
- Standard of care in most cases
- Radiation is an important adjunct to surgery decreasing local recurrence
  - 50 Gy pre-op and 66 Gy postop is standard dose for soft-tissue sarcomas
- Chemotherapy may be administered in some cases
- 50-60% 5-year survival
Amputation
- Indication
  - If unable to resect tumor with negative margins
  - Resection would result in irreversible damage to major nerves
  - Patient comorbidities limit potential for recovery after limb-sparing surgery
- Good prognosis in absence of metastatic disease

Answer 76

A

Classification - Malignant (fat)
* 2nd most common soft tissue tumour (behind UPS)
Subtypes

Dedifferentiated liposarcoma
- Result of malignant transformation of ALT/WDL
- 18% of liposarcomas
Myxoid liposarcoma
- Continuum from low-grade well-differentiated myxoid tumours to high grade poorly differentiated round cell tumours
- <20% of liposarcomas
- Most common in lower extremity
  - 2/3 in deep thigh
- Can metastasize to sites other than lung including retroperitoneum (mets to fat)
- CT chest/abdo/pelvics required for staging
Pleomorphic liposarcoma
- 5-15% of liposarcomas
- Older patients (>60)
- 2/3 in extremities
  - Most deep to fascia, 25% subcutaneous

Imaging
* MRI
- Heterogeneous
- T1 = hypointense
- T2 = hyperintense
- Post-gad = heterogeneous enhancement
  * CT Chest
- To assess for lung mets
- Myxoid liposarcoma requires CT C/A/P
Histology

Dedifferentiated
- Discrete areas similar to UPS/fibrosarcoma adjacent to ALT/WDL
Myxoid
- Lipoblasts within myxoid stroma
  - Lipoblast (signet ring-type cell) is a hallmark of liposarcomas
Pleomorphic
- Lipoblasts in background of high-grade pleomorphic sarcoma
  - Lipoblasts differentiate from UPS

Genetics

Dedifferentiated = MDM2 and CDK4 amplification
Myxoid = t(12;16) translocation –> FUS-DDIT3(CHOP)

Treatment

Well differentiated = marginal resection
Intermediate and high grade = treat as soft tissue sarcoma
- Wide surgical resection with cuff of normal tissue (>1cm)
- Radiation - Pre (~50Gy) or postop (~66Gy)
- Chemotherapy for high grade, large tumours and mets
Myxoid
- Responsive to chemo and radiation
  - Especially if high round cell component
  - Particularly useful in reducing tumour size

Prognosis

Dedifferentiated
- Local recurrence >40%
  - ~100% in retroperitoneum
- Distant mets in 15-20%
  - Most common = lungs, then liver
- 5y mortality = 30%
- Anatomic location best predictory of outcome
  - Retroperitoneal is the worst
Myxoid
- Depends on % of high grade/round cell component
- Low grade has <10% metastatic risk
- High grade has <35% metastatic risk and mortality rate
  - Poor prognostic factors
    - >10cm
    - >25% round cell component
    - Age>45
    - Spontaneous necrosis
Pleomorphic
- Metastatic rate <50%
- 5y survival = 60%
- Superficial tumours have better prognosis
  - Local recurrence <10%
  - 0% mets
- Poor prognostic factors
  - Large
  - Retroperitoneal
  - Older patient

Answer 77

A

Classification - Malignant (fibrogenic)
* Same as MFH - Malignant Fibrous Histiocytoma
Age - 30-80
Presentation

Most common = slow growing, painless mass
- Symptomatic when >10cm

Imaging
* MRI = deep seated inhomogeneous mass
Histology
* Fasiculated growth pattern
* Spindle-shaped cells with scant cytoplasm and indistinct borders
* Cells separated by interwoven collagen fibers
* Tissue may be organized in herringbone fashion
Treatment
* wide local resection with perioperative radiation

indications

* Add radiation if tumor is \> 5 cm (5000 cGy before resection and 2000 cGy after resection) * Local adjuvant treatment
* Phenol or cryotherapy

Answer 78

A

Classification - Malignant (fibrogenic cutaneous)
Age - 20-50
Presentation

Most common = slow growing, painless mass
- Composed of firm irregular nodules
- May have dark red or blue discoloration
  1. Location
Trunk > proximal extremities > head/neck
5. Imaging
Radiographs
- CXR to screen for lung mets in high-risk cases
  - i.e. recurrence or suspicion for a fibrosarcoma variant of DFSP
MRI
- Preop assessment in larger or atypical lesions and recurrent disease
Ultrasound
- Monitoring of local DFSP or regional lymph node metastasis
PET
- Monitoring of metastatic disease
  1. Histology
Biopsy required for diagnosis
Classically = uniform fibroblasts arranged in storiform pattern around an inconspicuous vasculature
- Bednar variant has scattered melanin-containing dendritic cells
Fibrosarcomatous variant has a characteristic herringbone pattern
7. Genetics
Mutations associated with t(17;22)
- Encodes for PDGF-beta chain (PDGFB)/collagen type I alpha 1 (COL1A1) fusion protein

Treatment

Imatinib
- 65% response rate
  - No response in patients who lack the t(17,22) mutation
- Indicated in adult patients with unresectable, recurrent, and/or metastatic DFSP
- Inhibits PDGF-receptor tyrosine kinase
Wide surgical resection +/- adjuvant radiation therapy
- Adjuvant radiation therapy is useful in patients with positive margins or in whom adequate wide excision alone may result in major cosmetic or functional deficits
- 15.7% recurrence for lesions on the body
- 51.8% recurrence rate for lesions on the head/neck

Prognosis

Local recurrence is common
Distant metastasis is rare (< 5%)
- Lung is the most common site
- Occurs via hematogenous spread
- Usually preceded by multiple local recurrences
Worse prognosis:
- Regional lymph node involvement
- Fibrosarcomatous progression DFSP variant
- Histologic features: high number of mitotic figures, increased cellularity, DNA aneuploidy, TP53 gene overexpression, and the presence of fibrosarcomatous changes
- Age > 50 years old

Answer 79

A

Classification - Malignant
* Unknown origin - not synovial
Age = 15-40
Presentation
* Slow growing mass, 50% have pain
Location

Arises near joints but rarely involves a joint
Most common = knee, shoulder, arm, elbow, foot
- Most common malignant sarcoma of the foot
Can metastasize to regional lymph nodes
- Lung mets still more common

Imaging

Radiographs = calcification in ~20%
MRI = indeterminate
- T1 = low signal
- T2 = high signal

Histology

Biphasic appearance with two cell types
- Spindle cells
- Epithelial cells

Genetics

t(X;18) chromosomal translocation
SYT-SSX1, 2, or 4 fusion protein

Treatment

Same as soft tissue sarcoma
- Wide surgical resection with cuff of normal tissue (>1cm)
- Radiation - Pre (~50Gy) or postop (~66Gy)
- Chemotherapy for high grade, large tumours and mets

Answer 80

A

Most common soft tissue sarcoma of the hand/wrist
CA125 highly expressed in tumour
Firm, painless nodule often confused with RA nodule, granuloma, or skin cancer

Answer 81

A

Has ability to produce melanin

Answer 82

A

Classification - Malignant (mesenchymal)
* Most common soft tissue sarcoma in children
4 subtypes

Embryonal – occurs in infants and young children
Alveolar – occurs in adolescents and young adults
- t(2;13) translocation
Botryoid – occurs in infants and young children
Pleomorphic – occurs in adults (40-70)

Histology
* Immunohistochemistry postive for desmin, myoglobin, MyoD1
Treatment

Pleomorphic = as for soft tissue sarcoma
- Wide surgical resection with cuff of normal tissue (>1cm)
- Radiation - Pre (~50Gy) or postop (~66Gy)
- Chemotherapy for high grade, large tumours and mets
Pediatric rhabdomyosarcoma = chemotherapy and wide surgical excision

Answer 83

A

• 50% associated with NF-1

Patients with NF-1 have 5% risk of malignant transformation

• Treat as soft tissue sarcoma

Wide surgical resection with cuff of normal tissue (>1cm)
Radiation - Pre (~50Gy) or postop (~66Gy)
Chemotherapy for high grade, large tumours and mets

Answer 84

A

Classification - Benign (Bone/periosteum)
Age = presents before age 40
Presentation

Pain, decreased ROM, contractures
Fibrosis of skin common with tense, erythematous, indurated skin

Location
* Most common = lower extremities
Imaging

Radiographs = cortical hyperostosis
- ‘Dripping candle wax appearance’
- May flow across joints

Treatment

Analgesics
Hyperostotic bone resection with contracture release
- Reserved for severe contractures, limited mobility, and pain

Answer 85

A

Classification - Benign peripheral nerve sheath tumour
Population - Patients with NF
Presentation

May be painful
Firm, possibly tender
- Tinel’s sign at mass
Mobile in transverse plane but not longitudinal plane

Imaging

MRI
- Enhancing heterogeneous lesion
- Target sign on T2
  - Circumferential high signal (myxoid) around centre of low signal (nerve fibres)
- Serial MRI used for monitoring for degeneration to malignancy
- To differentiate from Schwannoma:
  - Schwannoma are eccentric to nerve fibres
  - Solitary neurofibromas are central to nerve fibres

Genetics

Associated with inactivation of NF1 tumor suppressor gene (17q11.2)
Loss of expression of protein neurofibromin
Neurofibromin negatively regulates RAS-mediated pathway
Loss of neurofibromin leads to increased RAS activity
Affects RAS-dependent MAPK activity which is essential for osteoclast function and survival
Rapid hyperplasia of nonmyelinating Schwann cells into neurofibromas after NF1 inactivation
- Recruits perineural cells, fibroblasts, mast cells, endothelial cells

Treatment

Observe if asymptomatic
Surgical resection if symptomatic
- May require nerve grafting

DDx

MPNST (malignant peripheral nerve sheath tumor or neurofibrosarcoma)
- 5% of patients with NF, 10-25% lifetime risk
- Symptoms include painful, enlarging soft tissue mass
- Usually from plexiform neurofibroma
  - 10% of plexiform neurofibromas transform into MPNST
- Associated with loss of expression of CDKN2A or TP53 genes in non-myelinating Schwann cells (that also have biallelic inactivation of NF1)
- Poor prognosis
  - Widespread metastasis
  - High rate of local recurrence