Metabolic & Paget’s

Question 1

11. A plain radiograph of an adult pelvis shows a widened pubic symphysis. Which of the following is a cause of widening rather than fusion of the symphysis pubis?

A. Hyperparathyroidism

B. Osteoarthritis

C. Late ankylosing spondylitis

D. Alkaptonuria

E. Fluorosis

Answer 1

A. Hyperparathyroidism

Hyperparathyroidism is a cause of widening of the pubic symphysis. Other causes of widening include pregnancy, trauma, osteitis pubis, osteolytic metastases, infection, early ankylosing spondylitis, rheumatoid arthritis.

Question 2

13. Which of the following is a cause of acroosteosclerosis rather than acroosteolysis?

A. Psoriasis

B. Diabetes

C. Polyvinylchloride work

D. Hodgkin’s

E. Hyperparathyroidism

Answer 2

D. Hodgkin’s

Acrosteolysis is a lytic destructive process involving the distal and middle phalanges with no periosteal reaction.

Question 3

31. A 42-year-old man with Type 1 diabetic nephropathy, neuropathy and retinopathy develops sudden onset pain in the thighs. A diagnosis of diabetic myopathy is considered. Which is the single best answer?

A. Fever is present in most cases

B. Both lower limbs are affected in most cases

C. Low signal on unenhanced T1 indicated haemorrhagic infarction

D. SI is usually low on T2

E. A focus of central low SI surrounded by a rim of high SI on contrast enhanced T1 indicates muscle infarction and necrosis

Answer 3

E. A focus of central low SI surrounded by a rim of high SI on contrast enhanced T1 indicates muscle infarction and necrosis

Diabetic myopathy typically presents with sudden onset pain and swelling of the affected muscles and a palpable painful mass in 1⁄3 of cases. Fever is present in 10%. Other complications of diabetes are usually present.

Myopathy affects bilateral lower limbs in 18%.

It usually demonstrates diffusely high SI on T2 with areas of high SI on T1 indicating haemorrhagic infarction.

Question 4

37. A 37-year-old female with generalised bone pain and a chronic disease has plain films of the thoracic spine showing diffuse sclerosis and band-like areas of sclerosis involving the upper and lower endplates. Anterior erosions are noted in the vertebral bodies. A small lytic lesion is seen in the pedicle. Which is the diagnosis?

A. Fluorosis

B. Osteopetrosis

C. Systemic mastocytosis

D. Renal osteodystrophy and secondary hyperparathyroidism

E. Myelofibrosis

Answer 4

D. Renal osteodystrophy and secondary hyperparathyroidism

A rugger-jersey spine is described with subligamentous resorption and lytic brown tumour

Question 5

38. A 68-year-old man has a pelvic radiograph showing an enlarged right iliac bone with mixed lucency and areas of increased density. There are coarsened trabeculae and cortical thickening. There is thickening of the right ileopectineal line. Intense uptake is seen in this region on bone scan. He is known to have prostate cancer, currently on active surveillance. Prostate Specific Antigen (PSA) is stable at 1.7. Which is the diagnosis?

A. Melorheostosis

B. Metastatic prostate cancer

C. Post-radiotherapy changes from treated bony metastases

D. Mixed phase Paget’s disease

E. Myelofibrosis

Answer 5

D. Mixed phase Paget’s disease

Lytic, mixed and sclerotic phases are recognised in Paget;s, in which the lytic and mixed types show increased activity, and a variable pattern in the sclerotic type.

Question 6

43. A 28-year-old female with severe pain in both hips has a plain radiograph which demonstrates marked periarticular loss of cancellous bone. Considering transient regional osteoporosis, which of the following is most correct?

A. Radiographic changes occur before bone scan changes

B. Slowly developing osteoporosis

C. Usually resolves in 4-6 weeks

D. Joint space narrowing occurs late

E. Acetabulum is usually involved

Answer 6

D. Joint space narrowing occurs late

MR shows marrow oedema of the femoral heads, but does not usually involve the acetabulum.

Question 7

46. Which of the following favours primary rather than secondary hyperparathyroidism?

A. Brown tumour

B. Osteosclerosis

C. Rugger-jersey spine

D. Soft tissue calcification

E. Vascular calcification

Answer 7

A. Brown tumour

Brown tumours and chondrocalcinosis are features of primary hyperparathyroidism.

Question 8

(CNS) 20) A 78-year-old male patient presents with signs of acute lumbar myelopathy. Lumbar spine radiographs show collapse of the L3 vertebral body, which is encroaching upon the spinal canal. Additionally, throughout the remaining visualized vertebral bodies, there is diminished density of the central trabecular bone with relative preservation of the cortex and thickening of the marginal trabeculations, which appear coarse. What is the most likely underlying condition of bone?

a. Paget’s disease

b. pyknodysostosis

c. osteopetrosis

d. Gaucher’s disease

e. hyperparathyroidism

Answer 8

a. Paget’s disease

The described appearance is of ‘picture-frame’ vertebral bodies and is seen in Paget’s disease.

The central osteoporosis can lead to insufficiency fractures and complications thereof.

‘Rugger jersey spine’ has a similar appearance due to sclerosis of the endplates (but the anterior and posterior cortices are spared) and is seen with both hyperparathyroidism (usually secondary and associated with renal failure) and osteopetrosis.

Pyknodysostosis is a congenital disorder with sclerosis of long bones, causing obliteration of the medullary canal.

Gaucher’s disease causes osteosclerosis secondary to bone infarcts, often causing H-shaped vertebra due to central endplate collapse.

Question 9

25) Looser’s zones – transverse linear lucencies representing areas of poorly mineralized osteoid – are seen with which underlying pathological process of bone?

a. fracture

b. osteomyelitis

c. osteoporosis

d. osteopetrosis

e. osteomalacia

Answer 9

e. osteomalacia

Looser’s zones or Milkman’s pseudofractures are seen as linear lucencies in the bone due to incomplete fractures that have nonmineralized osteoid deposited within them.

The underlying failure of bone to mineralize is termed ‘osteomalacia’ (which means bone softening), and is most often due to vitamin D deficiency.

Rickets is osteomalacia in an immature skeleton.

The most common conditions resulting in an osteomalacic process and inadequate bone mineralization include renal osteodystrophy and vitamin D deficiency due to malnutrition/malabsorption of vitamin D or phosphate.

Question 10

26 A 32 year old previously well woman presents with a 4 week history of unilateral hip pain. There is no history of trauma or evidence of sepsis. Plain film shows marked unilateral osteoporosis of the femoral head and neck with loss of the subchondral cortex of the femoral head and neck. Which of the following statements is incorrect with regard to the most likely diagnosis?

(a) This condition is more common on the left side

(b) Joint space narrowing is a common feature

(c) Increased uptake on bone scintigraphy is typical

(d) It is more common in men

(e) A small joint effusion on MRI is often seen

Answer 10

(b) Joint space narrowing is a common feature

Transient osteoporosis of the hip is a self limiting disease of unknown aetiology typically affecting one joint at a time.

Bone marrow oedema is seen on MRI. Joint space narrowing is not a feature.

It is associated with pregnancy although still more common overall in middle aged men.

Question 11

28) Osteoporosis circumscripta – well-defined geographic lytic lesions in the skull – represents the early stages of which condition?

a. Paget’s disease

b. hyperparathyroidism

c. multiple myeloma

d. senile osteoporosis

e. sickle cell disease

Answer 11

a. Paget’s disease

Paget’s disease is a common progressive disorder of osteoclasts and osteoblasts resulting in bone remodelling.

It is usually polyostotic and asymmetrical, and affects 10% of those aged over 80.

Osteoporosis circumscripta is seen in the initial phase of Paget’s disease, which is characterized by an aggressive, predominantly lytic process with intense osteoclastic activity causing bone resorption.

Bone marrow is replaced by fibrous tissue with large vascular channels.

Geographic osteoporosis is seen in the skull and long bones, where the characteristic feature is a flame-shaped radiolucency beginning in a subarticular location and progressing into the diaphysis.

The disease then progresses through a mixed phase to a quiescent inactive late stage where bone turnover is decreased.

The skull is involved in 29–65% of cases, most commonly the anterior calvarium.

Question 12

(CNS) 29) An 85-year-old female presents with low back pain and is tender over the sacrum. Radiographs show a generalized reduction in bone density. MRI demonstrates symmetrical, bilateral, linear areas of signal abnormality in the sacral alae, which are low signal on T1W and high signal on STIR images. There is no history of trauma, but the patient does have a history of radiotherapy for cervical carcinoma many years previously. What is the most likely diagnosis?

a. insufficiency fracture

b. metastases

c. ankylosing spondylitis

d. Reiter’s syndrome

e. post-radiotherapy change

Answer 12

a. insufficiency fracture

Insufficiency fractures tend to occur in elderly female patients and manifest with pain. They are notoriously difficult to diagnose on plain film due to overlying soft tissues and bowel gas.

MR and bone scans demonstrate them well, often in an ‘H’ configuration (Honda sign).

Metastases tend to cause multiple focal areas of change.

Ankylosing spondylitis and Reiter’s syndrome are known causes of sacroiliitis, which would cause changes on MRI more localized to the iliac sides of the sacroiliac joints.

Post-radiotherapy changes tend to be those of fatty marrow replacement, with high signal on both T1W and T2W, and low signal on STIR images.

Question 13

56) Bilateral hand radiographs performed in a 70-year-old man for painful and stiff joints reveal a symmetrical periosteal reaction involving the metacarpals, increased soft tissue of the fingertips, and an increase in the longitudinal curvature of the fingernails. Which additional imaging investigation is most appropriate?

a. CTof the hands

b. MRI of the hands

c. isotope bone scan

d. radiograph of the chest

e. radiographs of the shoulders

Answer 13

d. radiograph of the chest

Hypertrophic pulmonary osteoarthropathy (HPOA) is a clinical syndrome of osteitis of the long bones, arthritis and digital clubbing of the fingers and toes.

It is most commonly associated with lung cancer (affecting 3–10% of patients) or other chronic pulmonary or pleural disease.

The underlying mechanism has not been established with certainty, but autonomic nervous or endocrine stimulation by tumours is postulated, with hormones such as oestrogen, adrenocorticotrophic hormone and growth hormone implicated.

In patients presenting with HPOA, approximately 80% have an underlying lung cancer, 10% a pleural tumour and 5% another intrathoracic malignancy. Other causes include chronic, suppurative, pulmonary inflammatory disease and congenital cyanotic heart disease.

Typical radiographic appearances are of a lamellar periosteal reaction affecting the diametaphyseal regions of the long bones, particularly the dorsal and medial aspects.

Bone symptoms and radiographic signs frequently regress following treatment of the underlying cause.

Question 14

@# 69) Plain radiographs of the knees are performed in a teenage girl with growth retardation and painful, deformed lower limbs. Which radiographic finding would suggest a diagnosis of scurvy rather than rickets?

a. pathological fractures

b. bowing deformity

c. widened growth plate

d. frayed metaphysis

e. sclerotic epiphyseal rim

Answer 14

e. sclerotic epiphyseal rim

Rickets is a deficiency of vitamin D in a child that results in osteomalacia of the immature skeleton.

Scurvy is a deficiency of vitamin C and is a disorder of collagen synthesis that can occur in children or adults.

Pathological fractures may be seen in both conditions.

Ground-glass osteoporosis is characteristic of scurvy, with other features including

a sclerotic line in the metaphyseal zone of preparatory calcification (white line of Frankel),

a radiolucent zone immediately to the diaphyseal side of the white line (Trummerfeld’s zone),

corner fractures (Parke’s corner sign)

and a sclerotic ring around the epiphysis (Wimberger’s sign).

In addition, bleeding diathesis is seen in scurvy; therefore, subperiosteal haematoma and haemarthrosis are also features.

Question 15

@# 87) On plain radiographs of the long bones or the spine, which of the following is not a recognized cause of a ‘bone within a bone’ appearance?

a. infant physiology

b. sickle cell anaemia

c. nutritional disturbance

d. renal osteodystrophy

e. metastatic disease

Answer 15

d. renal osteodystrophy

‘Bone within a bone’ is a term used to describe a radiographic appearance in which one bone appears to arise within another. It can be a physiological finding in a neonate or infant due to new bone formation. Pathological conditions that can cause the appearance include periosteal new bone formation, cortical splitting, subcortical osteopenia, altered bone growth, impairment of osteoclastic activity, altered bone metabolism, crystal deposition, and iatrogenic and technical radiological factors. It is not a feature of renal osteodystrophy but is seen in hypervitaminosis D and in healing rickets.

Question 16

96) A 30-year-old woman in the third trimester of pregnancy complains of a 4-week history of gradual onset of pain in the left hip following minor trauma. Radiographs show a normal-appearing joint space, mild osteopenia of the femoral head and neck, and an indistinct subchondral femoral head. On subsequent MRI, the bone marrow in the affected regions returns patchy but diffuse low signal on T1W and high signal on T2W images. There is a similar small area of marrow abnormality in the acetabulum, and a small hip effusion is seen. What is the most likely diagnosis?

a. septic arthritis

b. infarction

c. reflex sympathetic dystrophy

d. rheumatoid arthritis

e. transient osteoporosis

Answer 16

e. transient osteoporosis

Transient osteoporosis of the hip is part of the bone marrow oedema syndromes that also encompass migratory regional osteoporosis and transient bone marrow oedema.

The condition is spontaneous and selflimiting, clinical recovery occurring in several weeks to months with no specific treatment, although radiographic changes lag behind.

It is seen in pregnant women in the third trimester and middle-aged men.

The radiographic hallmark is the loss of subchondral cortex in the femoral head, and marrow oedema is seen on MRI with intense uptake of 99mTc-labelled diphosphonates on bone scintigraphy.

The aetiology is uncertain, but speculation has been made that the bone marrow oedema syndromes are related to reflex sympathetic dystrophy.

The appearance of transient osteoporosis of the hip may be mimicked by osteonecrosis.

Question 17

@# 4 .A stress fracture in which of the following areas would be most indicative of a pseudofracture (Looser’s zone) of osteomalacia?

(a) Axillary margin of the scapula

(b) Distal 1/3 ulna

(c) Greater trochanter of the femur

(d) Lateral femoral neck

(e) Proximal 1/3 radius

Answer 17

(a) Axillary margin of the scapula

Pseudofractures (Looser’s zones) are insufficiency stress fractures with poor healing due to mineral deficiency. These are classically associated with osteomalacia, but can also be due to Paget’s disease, osteogenesis imperfecta, or fibrous dysplasia. The fractures are typically bilateral and symmetrical and are at right angles to the cortical margin. Other common locations include distal 1/3 radius, proximal 1/3 ulna, lesser trochanter, medial femoral neck, ischial tuberosity, clavicle, long bones of the feet and hands.

Question 18

14 A patient presents with painful swelling of the limbs and joints, particularly the knees, ankles, wrists and elbows. Digital clubbing and joint effusions are noted. Plain radiographs show marked bilateral, smooth periosteal reactions affecting the radius, ulna, tibia and fibula. Which one of the following diseases is not associated with the most likely unifying condition?

(a) Gaucher’s disease

(b) Carcinoma of the bronchus

(c) Undifferentiated nasopharyngeal carcinoma

(d) Pleural fibroma

(e) Ulcerative colitis

Answer 18

(a) Gaucher’s disease

The patient is most likely to be suffering from hypertrophic osteoarthropathy. This is commonly secondary to disease within the chest but many extra-thoracic causes are also recognised. Possible thoracic causes include: Bronchogenic carcinoma, lymphoma, pulmonary metastasis, a benign tumour (e.g. pleural fibroma), and chronic inflammation/infection (e.g. an abscess, bronchiectasis). Extrathoracic causes include, amongst others: inflammatory bowel disease, whipple’s disease, coeliac disease, cirrhosis, dysentery and undifferentiated nasopharyngeal carcinomas.

Question 19

18 A pregnant lady suffers from sudden, spontaneous hip pain, worsened by weight bearing. The range of movement is relatively well preserved. Plain radiographs and an MR examination are performed. Which of the following would be more suggestive of avascular necrosis rather than transient osteoporosis of the hip?

(a) Acetabular oedema on MR imaging

(b) A ‘double line’ sign on MR imaging

(c) Osteoporosis on plain radiographs

(d) Increased uptake in the femoral head on 99mTc-MDP imaging

(e) Preservation of the articular cartilage on MR imaging

Answer 19

(b) A ‘double line’ sign on MR imaging

Transient osteoporosis of the hip is a sudden, painful but self limiting condition, first described in patients in the third trimester of pregnancy, but seen most frequently in middle-aged men.

Radiographs show diffuse ostepaenia 4-8 weeks after symptom onset.

MR imaging demonstrates diffuse oedema, without focal defects:

oedema localized to the subchondral surface or a ‘double-line’ sign suggest AVN.

99mTcMDP imaging shows homogeneously increased uptake in the femoral head and neck.

Question 20

42 A patient with Paget’s disease has a series of plain radiographs. Which of the following is a feature of the active phase of the disease?

(a) Widened and coarsened trabeculation of the pelvic ring

(b) ‘Cotton wool’ skull

(c) ‘Ivory vertebra’

(d) Osteoporosis circumscripta

(e) Splitting of the iliopectineal line

Answer 20

(d) Osteoporosis circumscripta

The active phase is the osteolytic phase, also known as the ‘hot’ phase.

Typical lesions include osteoporosis circumscripta of the skull (especially frontal and occipital bones) and well-defined, ‘flame-shaped’ radiolucencies of the long bones.

Question 21

6 You review a series of plain radiographs of a male patient taken over the course of 25 years. There is irregular, solid, bilateral, symmetrical periosteal proliferation of the distal long bones. These appearances developed in his adolescence, and have been stable since. You are told that this is relatively pain-free. What is the most likely diagnosis?

(a) Pachydermoperiostitis

(b) Diffuse idiopathic skeletal hyperostosis

(c) Fluorosis

(d) Secondary hypertrophic osteoarthropathy

(e) Vascular insufficiency

Answer 21

(a) Pachydermoperiostitis

Pachydermoperiostosis, also known as primary hypertrophic osteoarthropathy, is an autosomal dominant condition resulting in a bilateral, symmetrical periosteal reaction of the distal long bones. This typically develops in young men and spontaneously arrests in adulthood. Compared to secondary hypertrophic osteoarthropathy, the periosteal reaction is more solid and relatively painless.

Question 22

9 The radiographs of an elderly patient demonstrate the expansion of a long bone, with cortical bone thickening and coarse trabeculation. Pagets’s disease is suspected. Further investigations were performed in the nuclear medicine department. Which of the following is not typical?

(a) Marginal uptake of 99mTc-MDP in lytic lesions

(b) Deformity of bones

(c) Normal uptake of 99mTc-MDP in some sclerotic lesions

(d) Increase uptake of 99mTc-MDP in the active phase

(e) Increased uptake of 99mTc-sulphur colloid by bone marrow

Answer 22

(e) Increased uptake of 99mTc-sulphur colloid by bone marrow

Uptake of 99mTc-sulphur colloid is reduced due to the replacement of bone marrow by fibrovascular tissue.

Question 23

14 A 32 year old woman undergoes a CXR after developing a cough. The CXR is unremarkable except for bilateral superior rib notching affecting multiple ribs. Which of the following is least likely?

(a) Hypoparathyroidism

(b) Rheumatoid arthritis

(c) Scleroderma

(d) Systemic lupus erythematosus

(e) Marfan’s syndrome

Answer 23

(a) Hypoparathyroidism

Hyperparathyroidism is a cause of both superior and inferior rib notching, but not hypoparathyroidism.

Question 24

35 A 28 year old man undergoes a CXR for occupational purposes. The lung parenchyma is clear, but the ribs are noted to be diffusely sclerotic. Which of the following does not cause bone sclerosis?

(a) Fibrous dysplasia

(b) Acromegaly

(c) Mastocytosis

(d) Tuberous sclerosis

(e) Fluorosis

Answer 24

(b) Acromegaly

Acromegaly, along with Cushing’s disease and scurvy are acquired causes of lucent ribs. Other causes of dense ribs include osteopetrosis, subperiosteal rib resection, chronic infection and trauma.

Question 25

(CNS) 46 A 65 year old man has a pelvic X-ray following a fall. No fracture is identified. However, incidental note is made of thickening of the trabeculae in the ilium along with acetabular protrusion and thickening of the iliopectineal line. ‘ Which of the following features are not seen in this condition?

(a) Picture frame vertebra

(b) Ivory vertebra

(c) Diploic widening of skull

(d) ‘Cotton wool’ appearance of the skull

(e) ‘Hair-on-end’ appearance of skull

Answer 25

(e) ‘Hair-on-end’ appearance of skull

The exact appearance of Paget’s disease depends on which phase it is in (active, mixed or quiescent). It may be complicated by malignant degeneration, fracture or neurological entrapment. ‘Hair-on-end’ appearance is seen in thalassaemia, hereditary spherocytosis and sickle cell disease amongst others.

Question 26

@# 72 A 56-year-old woman is found to have uniform osteopaenia, cortical thinning, acetabular protrusion, indistinct trabeculae and pseudofractures involving the femoral necks on a pelvic radiograph. Which of the following is least likely to cause these appearances is?

(a) Paraneoplastic syndrome

(b) Biliary disease

(c) Phenobarbitone

(d) Dietary phosphorous deficiency

(e) Renal tubular acidosis

Answer 26

(a) Paraneoplastic syndrome

These are the classic radiographic findings of osteomalacia. Other causes relate to interference with vitamin D metabolism such as previous partial gastrectomy, or decreased calcium deposition in bone such as in bisphosphonate treatment in Paget’s disease.

Question 27

6. A 60 year old woman presents to her GP with renal colic and hypercalcaemia. She has the following findings on plain film: subperiosteal bone resorption of the proximal phalanges of the hands, chondrocalcinosis of the articular cartilage at the knee joints, and a well-defined lytic lesion in the body of the mandible. The most likely unifying diagnosis is:

a. Parathyroid adenoma

b. Parathyroid carcinoma

c. Renal osteodystrophy

d. Osteomalacia

e. Myeloma

Answer 27

6. a. Parathyroid adenoma

Parathyroid adenoma would be the most likely cause of primary hyperparathyroidism. Parathyroid carcinoma would produce a similar radiographic picture but is much less common. Brown tumours are seen in both primary and secondary hyperparathyroidism and are most common in the mandible, ribs and pelvis; they have a variable appearance on MRI and may simulate primary or secondary neoplasms.

Question 28

23. An elderly gentleman complaining of generalised aching in his lower limbs is shown to have bilateral distal tibial periostitis. There is no underlying bone lesion identified. Which of the following would be the most likely explanation?

a. Arterial insufficiency

b. Thyroid acropachy

c. Trauma

d. Pachydermoperiostosis

e. Hypertrophic pulmonary osteoarthropathy

Answer 28

23. e. Hypertrophic pulmonary osteoarthropathy

The most likely explanation is hypertrophic osteoarthropathy.

Thyroid acropachy changes usually occur in the upper limb.

Venous stasis is a cause of periostitis rather than arterial insufficiency.

Trauma would be unlikely to be bilateral unless there was a specific history.

Pachydermoperiostitis is the idiopathic form of hypertrophic osteoarthropathy, it usually presents around adolescence and is usually associated with clubbing.

Question 29

29. A 70 year old male presents with increasing pain in his right hip over the past month. There is no specific history of trauma. A plain radiograph demonstrates the presence of an incomplete fracture of the femoral neck arising from the lateral (convex) side. What is the most likely underlying abnormality of the femoral neck?

a. Osteomalacia

b. Metastasis

c. Osteoid osteoma

d. Infection

e. Paget’s disease

Answer 29

29. e. Paget’s disease

Incremental fractures (banana fracture) along the convex side of the bone are classically associated with Paget’s disease. These most commonly occur in the femur where they cause lateral bowing, and the tibia where they cause anterior bowing. Compression fractures of the vertebrae are also associated with Paget’s.

Question 30

37. A 24 year old man suffers a short oblique fracture of his distal tibia from a direct blow during a football game. He is treated with an intramedullary nail with a good reduction being achieved. Fourteen days later the foot becomes very tender, red and swollen but all haematological and biochemical parameters remain normal. Plain radiographs show spotty osteoporosis and subchondral erosions. Which of the following is most likely diagnosis?

a. Disuse osteoporosis

b. Charcot joints

c. Infection

d. Regional sympathetic dystrophy

e. Rheumatoid arthritis

Answer 30

37. d. Regional sympathetic dystrophy

This is the typical appearance, history and imaging findings for regional sympathetic dystrophy. This may occur following fractures or secondary to other pathologies such as primary or secondary bone tumours. There is overactivity of the sympathetic nervous system causing pain, swelling and hyperaemia with excessive bone resorption. This is usually in a periarticular distribution and may simulate other disease processes.

Question 31

QUESTION 12 A pelvic radiograph reveals a symmetrical abnormality of the proximal femora characterised by thin lucent lines perpendicular to the medial femoral cortex, with a faint sclerotic margin. These linear lucent areas do not extend across the full width of the femur, and the visualised bones are otherwise of normal appearance. Which is the most likely diagnosis?

A Hyperparathyroidism

B Multiple myeloma

C Osteomalacia

D Osteoporosis

E Paget’ s disease

Answer 31

C Osteomalacia

Looser’s zones represent areas of unmineralised osteoid and are pathognomonic of osteomalacia. The medial aspects of the proximal femora are typical sites for Looser’s zones; other common sites include the pubic rami, ribs and the lateral border of the scapula.

Question 32

QUESTION 17
A 75-year-old lady undergoes bone mineral density (BMD) measurements at the hip and spine by means of dual energy radiograph absorptiometry (D:XA). What findings would satisfy the World Health Organisation (WHO) criteria for osteoporosis?

A BMD below the young adult reference mean

B BMD between -1 and - 2 .5 standard deviations below that of young adult reference mean

C BMD more than -2.5 standard deviations below the young adult reference mean

D BMD more than -2.5 standard deviations below the young adult reference mean, with one low-energy fracture

E BMD more than -2.5 standard deviations below the young adult reference mean, with two low-energy fractures

Answer 32

C BMD more than -2.5 standard deviations below the young adult reference mean

Question 33

QUESTION 21 A 50-year-old woman attends the Emergency Department following a minor hand injury. A plain radiograph reveals no fracture, but there is evidence of subperiosteal erosion along the radial aspect of the middle phalanges of the middle and index fingers. What is the most likely diagnosis?

A Gout

B Hyperparathyroidism

C Myeloma

D Sarcoid

E Systemic lupus erythematosus

Answer 33

B Hyperparathyroidism

Question 34

QUEESTION 30
An asymptomatic 65-year-old woman on long-term steroids for rheumatoid disease undergoes dual energy X-ray absorptiometry (DX.A). Her Z score is -2 and her T score is -2.7. What is the WHO definition of osteoporosis?

A T score less than -1

B T score less than -2.5

C Z score less than

D Z score less than -2.5

E Mean of T and Z score less than -2

Answer 34

B T score less than -2.5

density can be measured in relation to an age and sex-matched population (Z score) or in relation to a population of young adults of the same sex (T score). The WHO defines osteoporosis as a T score less than -2.5, therefore relating bone mineral density to sex-matched peak bone mass.

Question 35

QUESTION 43
A 65-year-old woman is referred for a pelvic radiograph to investigate intermittent right hip pain. The radiograph shows thin lucent lines within both inferior pubic rami. Which radiographic feature would support a diagnosis of osteoporotic fracture rather than osteomalacia?

A Callus formation

B Failure to extend across the entire width of the bone

C Sclerotic margin to lucencies

D Similar appearances within the proximal femora

E Symmetrical appearance

Answer 35

A Callus formation

Question 36

QUESTION 77
The skull radiograph of a 75-year-old man reveals a well-defined lyric area involving the frontal bone. A radiograph of the femur in the same patient shows a well-defined lucency extending from the articular surface to the diaphysis. The transition between lyric and normal bone is well defined and appears flame shaped. What is the most likely diagnosis?

A Acromegaly

B Fibrous dysplasia

C Myeloma

D Pager’s disease

E Skeletal metastases

Answer 36

D Pager’s disease

Paget’s disease is a condition of uncertain aetiology characterised by increased turnover and excessive remodelling of bone. Osteoporosis circumscripta and advancing flame-shaped lucencies within long bones are features characteristic of active osteolytic disease. Inactive disease is characterised by widespread sclerosis: cotton wool sclerosis in the skull, enlarged ivory vertebrae with cortical thickening and coarsened thick trabeculae within the long bones. Paget’s disease may be complicated by fractures, accelerated osteoarthritis and sarco1natous change.

Question 37

44. A 70-year-old man undergoes an x-ray of his right hand following trauma. There is no evidence of fracture, but incidental resorption of the middle portion of the distal phalanges is demonstrated. Which of the following would be the most likely underlying cause?

A. Scleroderma.

B. Frostbite.

C. Leprosy.

D. Polyvinyl chloride.

E. Psoriatic arthropathy.

Answer 37

44. D. Polyvinyl chloride.

This results in resorption of the middle portion of the terminal phalanx. The other answers cause resorption of the terminal tufts of the distal phalanges. Other causes of resorption of the terminal tuft include Raynaud’s, diabetes, syringomyelia, burns, trauma, epidermolysis bullosa, congenital phenytoin toxicity (in infants of epileptic mothers), and snake and scorpion venom. Hyperparathyroidism can cause tuft, mid-portion, and periarticular resorption; psoriatic arthropathy can cause tuft and periarticular resorption.

Question 38

61. A patient is referred from the dialysis unit with a history of joint and muscular pain. In particular they complain of bilateral hand pain and hip pain. The plain films of both hands show a loss of distinction of the radial aspect of the phalanges of the index and middle fingers. There is an area of para-articular soft tissue calcification noted adjacent to the middle finger metacarpal of the right hand. The pelvic x-ray is distinctly abnormal. There is a large expansile lucent lesion in the right iliac bone, which has a narrow zone of transition and no evidence of internal matrix. The bony definition of the rest of the pelvic bone reveals a coarsened trabecular pattern, but no evidence of expansion of the bones. There are multiple small linear lucencies noted along the medial aspect of the femurs bilaterally, which demonstrate a periosteal reaction. What condition do you think this patient has?

A. Primary hyperparathyroidism.

B. Tertiary hyperparathyroidism.

C. Paget’s disease.

D. Osteomalacia.

E. Renal osteodystrophy.

Answer 38

61. E. Renal osteodystrophy.

The first important observation to note is the referral route. A patient from the dialysis unit is going to have renal failure, thereby excluding tertiary hyperparathyroidism and making primary less likely. This leaves Paget’s disease, osteomalacia, and renal osteodystrophy. The patient clearly has features of both hyperparathyroidism (subperiosteal resorption, brown tumour in iliac bone) and osteomalacia (Looser’s zones), giving the diagnosis of renal osteodystrophy, which has features of both. Another feature of renal osteodystrophy is the soft-tissue calcification noted in the hand. The Looser’s zones are small stress fractures on the load-bearing aspect of a bone, caused by osteomalacia. This contrasts with the stress fractures seen on the tensile aspect of bones (i.e. lateral aspect of femur) seen in Paget’s disease and fibrous dysplasia. Whilst Brown tumours are more closely associated with primary hyperparathyroidism, the majority actually occur in secondary hyperparathyroidism as this disease is much more prevalent.

Question 39

63. A 62-year-old male with a known diagnosis of bronchogenic carcinoma presents with pain and swelling of his wrists. What radiographic features are consistent with hypertrophic pulmonary osteoarthropathy?

A. Metaphyseal lamellar periosteal reaction.

B. Irregular epiphyseal periosteal proliferation.

C. Asymmetrical, thick ‘feathery’ periosteal reaction.

D. Cortical thickening and trabecular coarsening.

E. Symmetrical, solid periosteal new bone formation.

Answer 39

63. A. Metaphyseal lamellar periosteal reaction.

Hypertrophic pulmonary osteoarthropathy is a paraneoplastic syndrome secondary to the release of vasodilators. It typically causes burning pain and swelling, with the ankles and wrists being most commonly affected. Pulmonary causes include bronchogenic carcinoma, mesothelioma, and pleural fibroma. Radiographs demonstrate cortical thickening and lamellar periosteal proliferation in a diametaphyseal location. Bone scintigraphy will demonstrate patchy linear increased uptake along the cortical margins. Option B describes pachydermoperiostosis, a self-limited condition in adolescents. Option C is typical of thyroid acropachy. Cortical thickening and trabecular coarsening is a feature of Paget’s disease and symmetrical, solid periosteal new bone formation is described in hypervitaminosis A.

Question 40

4 An otherwise well 84-year-old woman complains of left knee pain while away on an extended holiday with family and attends a local clinic for analgesia. As part of the work-up a radiograph is performed, which reveals chondrocalcinosis. She also remembers that she has been seen recently by a hospital endocrinologist but cannot remember any further details. What further underlying finding is likely?

a Hypocalcaemia

b Hyperthyroidism

C Hyperparathyroidism

d Hyperkalaemia

e Hypopituitarism

Answer 40

4 Answer C: Hyperparathyroidism

Calcium pyrophosphate dihydrate crystal deposition (CPPD) is frequently associated with osteoarthritis (OA), but is distinguished by the presence of chondrocalcinosis. This term describes the imaging appearances of the presence of calcium in cartilage; for example menisci, triangular fibrocartilage of wrist. Chondrocalcinosis may have other causes, therefore technically is not synonymous with CPPD. Common associations of CPPD are: hyperparathyroidism, hypothyroidism, haemochromatosis, hypomagnesaemia and haemosiderosis.

Question 41

15 An 80-year-old man presented with right hip pain following a fall was assessed initially with plain radiographs of his hip and pelvis and then a bone scan. What feature would be suggestive of Paget’s disease?

a Osseous expansion

b Cortical thinning

C Trabecular thinning

d Thinning of iliopubic and ilioischial lines

e Photopenic lesions on bone scan

Answer 41

15 Answer A: Osseous expansion

Paget’s is a multifocal skeletal process, which results from disordered and excessive bone remodelling. It has several stages: active, osteolytic phase, middle, mixed phase and an inactive, quiescent late phase. Radiography alone is only 13-74% sensitive. Scintigraphy and radiography are 60% sensitive. Bone scan alone is over 90% sensitive. Commonly affected areas are: skull, long bones, ribs, pelvis and spine. The key features are osseous expansion with thickening of the cortex and coarsening of the trabecular pattern.

Question 42

41 A 67-year-old man was noticed to have a mixed sclerotic and lucent region in his proximal tibia with bowing of the bone and marked thickening of the cortex. There was no periosteal reaction. What is the most likely diagnosis?

a Paget’s disease

b Aneurysmal bone cyst

c Rickets

d Non-ossifying fibroma

e Chondromyxoid fibroma

Answer 42

41 Answer A: Paget’s disease

A flame-shaped lucency and bone expansion with cortical thickening are typical features of Paget’s disease. An aneurysmal bone cyst would have thin, intact cortex and tends to affect the metaphysis. Non-ossifying fibromas usually present in children.

Question 43

7 A 62-year-old patient with non-specific bone pain is referred for a bone scan, which shows avid diffuse uptake in the right femur corresponding to a thickened cortical outline. The bone scan is otherwise normal for age. What is the most likely diagnosis?

a Monostotic fibrous dysplasia

b Monostotic Paget’s disease

c Osteomalacia and insufficiency fracture

d Myelofibrosis

e Osteosarcoma

Answer 43

7 Answer B: Monostotic Paget’s disease

These are typical appearances but radiological correlation should be performed.

Question 44

14 A 38-year-old female with a history of iron deficiency anaemia is seen in the Emergency Department following an alleged assault and has a skull radiograph to exclude the presence of a foreign body. What feature would be suggestive of a recurrence of her anaemia?

a Narrowing of diploe

b Hair-on-end appearance of skull

C Osteopenia of zygoma

d Osteosclerosis of sphenoid

e Biconcave vertebrae

Answer 44

14 Answer B: Hair-on-end appearance of skull

Iron deficiency anaemia is caused by deficient iron stores at birth, dietary deficiency or excess blood loss for example, due to menstruation or from the gastrointestinal tract. Features are: widening of diploe, hair-on-end appearance of skull, osteoporosis in long bones and absence of facial bone involvement. Biconcave vertebrae occur in sickle cell anaemia.

Question 45

15 An elderly woman with known Paget’s disease of her skull presented following a fall. According to her husband she had also been becoming more confused recently. What feature secondary to Paget’s disease is most likely?

a Osteoblastoma

b Cerebral hemisphere compression

C Hydrocephalus

d Hypocalcaemia

e Leukaemia

Answer 45

15 Answer C: Hydrocephalus

(Secondary to basilar impression) The four main categories for complications of Paget’s disease are: associated neoplasia, insufficiency fractures, neurologic entrapment, and early onset osteoarthritis. Neoplasia includes sarcomatous transformation, multicentric giant cell tumour or lymphoma. Banana fractures are tiny horizontal `Looser lines’ on convex surfaces of lower extremity long bones. Other insufficiency fractures include vertebral compression fractures. Neurologic complications involve either basilar impression leading to hydrocephalus and brainstem compression, or spinal stenosis.

Question 46

(CNS) 63 A 70-year-old male was seen in outpatients with left T12 nerve root pain. CT demonstrated generalised expansion of the whole of the T12 vertebra with coarsening of the trabeculae. On T1- weighted imaging there was effacement of the fat around the left T12 nerve root. What is the cause for these symptoms?

a Fibrous dysplasia

b Metastastatic disease

C Paget’s disease

d Haemangioma

e Langerhans cell histiocytosis

Answer 46

63 Answer C: Paget’s disease

Paget’s disease is characterised by abnormal and excessive remodelling of bone. The prevalence increases with age and the disease predominates in the axial skeleton. The disease occurs in three phases: osteolytic, mixed and osteoscle- rotic. Spinal involvement is common in the lumbar region and the vertebrae are enlarged with coarse trabeculae. Nerve entrapment and cord compression can occur. The differentials for a solitary expanded vertebra include GCT and ABC both of which are lyric and vertebral haemangiomas, which demonstrate a `polka dot’ appearance with little expansion.

Question 47

9 A 67-year-old man complains of pain in both wrists and ankles. The general practitioner discovers clubbing on digital examination. Plain radiographs are requested, which show changes consistent with hypertrophic osteoarthropathy (HOA). What is the most likely underlying finding in this patient?

a Adrenal adenoma

b Glioblastoma

c Thyroid carcinoma

d Nephroblastoma

e Bronchiectasis

Answer 47

9 Answer E: Bronchiectasis

Hypertrophic osteoarthropathy is a syndrome of proliferative periostitis of the long bones, digital clubbing and arthralgia. Symptoms include pain and swelling of the wrist and ankles. Non-small-cell lung cancer is the most common malignant association. HOA is cited to be present in 31 % of lung cancer patients and often precedes chest symptoms. Ectopic production of growth factors is thought to be the underlying causative factor. Other neoplasia in which HOA is seen include: pulmonary metastases (secondary to breast, nasopharyngeal tumours, renal cell carcinoma, melanoma, osteosarcoma) as well as benign conditions (benign pleural fibroma and bronchiectasis).

Question 48

16 A middle-aged man presented to the Emergency Department with right hip pain that had started suddenly a few weeks previously and resulted in decreased range of movement. Plain films showed osteoporosis of the hip joint and loss of the subchondral cortex of the femoral head with preservation of the joint space. What is the most likely diagnosis?

a Avascular necrosis

b Transient osteoporosis

C Synovial chondromatosis

d Disuse atrophy

e Villonodular synovitis

Answer 48

16 Answer B: Transient osteoporosis

This is a self-limiting disease of unknown aetiology. A characteristic is loss of subchondral cortex of the femoral head and neck region. Unlike other forms of arthritis, there is no joint space narrowing or subchondral bone collapse. Radiographic features include a joint effusion, increased uptake on bone scans, diffuse marrow oedema of the femoral head and neck (MR) and pathological fractures. There is usually spontaneous recovery within two to six months, but recurrence elsewhere is possible.

Question 49

6. An 80-year-old diabetic complains of left groin pain. He undergoes twice a week haemodialysis. The plain radiograph shows large globular periarticular calcifications around both hip joints. A bone scan shows absence of renal activity and ‘superscan’ appearance. The calcifications also show increased tracer uptake. The most likely cause of the calcifications is?

(a) Dermatomyositis

(b) Renal osteodystrophy

(c) Scleroderma

(d) Calcium pyrophosphate deposition disease.

(e) Renal osteodystrophy

Answer 49

6. (b) Renal osteodystrophy

Patients with renal osteodystrophy have extensive soft tissue calcifications, particularly in periarticular distribution. ‘Superscan’ appearance is also a feature.

Question 50

7. A 65-year-old woman with chronic rheumatoid arthritis, had fracture of the lateral malleolus which was treated by a cast immobilisation. Since removal of the plaster, the foot has been swollen and painful on movements. Plain radiographs show that the fracture is united but the bones show diffuse osteopenia with endosteal scalloping and severe periarticular demineralisation. Bone scan shows increased uptake on three phase scintigram. The most likely cause of the patient’s symptoms is?

(a) Reflex sympathetic dystrophy

(b) Transient regional osteoporosis

(c) Myelomatosis

(d) Infection

(e) Disuse osteoporosis

Answer 50

7. (a) Reflex sympathetic dystrophy

This is commonly associated with trauma. The condition causes hyperhidrosis skin changes with excessive pitting oedema, sudomotor changes (hyperhidrosis and hypertrichosis), pain and patchy osteopenia. Three-phase bone scan shows increased blood flow, increased blood pool and increased periarticular uptake on delayed images.

Question 51

14. A 40-year-old chronic smoker with recently diagnosed bronchogenic carcinoma presents with bilateral leg pains. A plain radiograph shows lamellar periosteal reaction in bilateral tibia. A bone scan demonstrates diffusely increased uptake along the cortical margins of the tibial diaphysis. The most likely diagnosis is?

(a) Bilateral tibial metastases

(b) Osteomyelitis

(c) Chronic venous stasis

(d) Hypertrophic osteoarthropathy

(e) Acromegaly

Answer 51

14. (d) Hypertrophic osteoarthropathy

This is seen in multiple conditions (e.g. malignant tumours of the lung, some benign lesions, chronic chest infections). The condition manifests as cortical thickening and lamellar periosteal reaction in the diametaphyseal regions of the long bones. Bone scanning shows symmetrical uptake along the cortical margins of the diaphysis and metaphysis of tubular bones.

Question 52

15. An elderly patient with history of urinary frequency and dribbling presents with right hip pain. A radiograph of pelvis shows there is marked thickening of the iliopectineal line with acetabular protrusion, coarsening of the trabecular pattern and increased sclerosis in the entire right hemipelvis. The left hemipelvis appears normal. The most likely diagnosis is?

(a) Sclerotic metastases from prostate carcinoma

(b) Paget’s disease

(c) Lymphoma

(d) Normal variant

(e) Fluorosis

Answer 52

15. (b) Paget’s disease

Asymmetrical cortical sclerosis and trabecular thickening is seen in Paget’s disease. Metastatic disease of the prostate is unlike to affect only a hemipelvis and does not directly cause acetabular protrusion. Fluorosis causes generalised sclerosis of the bones in the body

Question 53

20. A 67-year-old man with history of lung cancer and renal transplant had a bone scan. There are multiple focal areas of increased tracer uptake in the left ribs, arranged in a linear pattern. Increased tracer uptake is also identified along the cortices of both humerus and radius bones bilaterally. No renal uptake is seen. The most likely diagnosis for this appearance is?

(a) Hypertrophic osteoarthropathy with rib metastases

(b) Hypertrophic osteoarthropathy with rib fractures

(c) Normal uptake in lower limbs with rib fractures

(d) Normal uptake in lower limbs with rib metastases

(e) Diffuse skeletal metastases

Answer 53

20. (b) Hypertrophic osteoarthropathy (HPOA) with rib fractures

On bone scan multiple areas of uptake in a linear pattern suggests traumatic injury to ribs. HPOA is characterised by bilateral symmetrical tracer uptake on bone scanning, involving the diaphyseal and metaphyseal regions of long bones. Characteristically a periosteal reaction is seen along the shafts of involved bones. This pattern of uptake is called a ‘double-stripe’ or ‘parallel-track’ sign and is characteristic of HPOA.

Question 54

21. A 60-year-old man with history of diabetes, chronic renal failure and bilateral intermittent claudication, had a left ankle injury 6 months ago. It was treated by open reduction and internal fixation of the medial and lateral malleoli. He now complains of persistent pain and swelling in the ankle and foot. Plain radiographs show marked osteopenia of the bones in the left ankle and foot. Bone scan shows diffuse increased tracer uptake in the periarticular distribution in left ankle and foot.
    The likely cause of the bone scan appearances is?

(a) Chronic ischemic feet

(b) Hypertrophic osteoarthropathy

(c) Secondary hyperparathyroidism

(d) Reflex sympathetic dystrophy

(e) Diabetic foot

Answer 54

21. (d) Reflex sympathetic dystrophy

A history of trauma, periarticular uptake on bone scan and osteoporosis suggests reflex sympathetic dystrophy. All other conditions are likely to affect both feet.

Question 55

22. A 75-year-old woman presents with symptoms of headache, right leg pain and raised serum alkaline phosphatase. Plain radiography of the right leg shows cortical thickening of the proximal tibia with coarse trabeculations and bowing. A bone scan demonstrates intense tracer uptake in the calvarium and the right tibia. The most likely diagnosis is?

(a) Multiple myeloma

(b) Paget’s disease

(c) Secondary hyperparathyroidism

(d) Hypertrophic pulmonary osteoarthropathy

(e) Myelofibrosis

Answer 55

22. (b) Paget’s disease

Paget’s disease can be monostotic or polyostotic and demonstrates intense tracer uptake on bone scan. The area of uptake usually conforms well to the area of bone that is distorted or expanded. The most common bones involved are the pelvis, spine, skull, femur, scapula, tibia and humerus. Many patients are evaluated after finding increased serum alkaline phosphatase.

Question 56

27. A 30-year-old African man presents with knee pain. Radiograph shows a serpiginous area of lucency with sclerotic margins in the proximal metaphysis of tibia. MRI shows a ‘double-line’ sign on T2-weighted images. There is a linear area of low signal peripheral to a high signal intensity inner border. A bone scan shows no uptake in the area. The most likely diagnosis is?

(a) Bone infarct

(b) Osteomyelitis

(c) Enchondroma

(d) Non-ossifying fibroma

(e) Osteonecrosis

Answer 56

27. (a) Bone infarct

The radiographic and MRI appearances described are typical for a bone infarct. These are typically metaphyseal or diaphyseal in contrast to osteonecrosis. Bone scans may show increased uptake in acute stages where revascularisation has occurred.

Question 57

14. Which of the following are correct regarding congenital hypothyroidism ? (T/F)

(a) It is cause of posterior scalloping of the vertebral bodies.

(b) The incidence is higher in infants with Down’s syndrome.

(c) A radiolucent metaphyseal band is a feature.

(d) Sclerosis of the skull base occurs.

(e) It is more common in males.

Answer 57

Answer:

(a) Not correct
(b) Correct
(c) Not correct
(d) Correct
(e) Not correct

Explanation:

Hypothyroidism is 3 times more common in females.
In hypothyroidism, the bones are slender with endosteal thickening and typically with a dense band at the metaphysic.
There may be hypoplasia of the vertebral bodies, particularly at the level of the first or second lumbar vertebrae.
Posterior scalloping of the vertebral bodies is seen in acromegaly.

Question 58

25. The following statements are correct: (T/F)

(a) Paget’s disease has a prevalence of 10 % in people over the age of 80 years of age.

(b) Developmental dysplasia of the hip is more common in males

(c) Diffuse idiopathic skeletal hyperostosis commonly presents in children

(d) The highest incidence of fibrous dysplasia is between 30-50 %years of age.

(e) Ankylosing spondylitis is found more commonly in Black than Caucasian populations

Answer 58

Answers:

(a) Correct
(b) Not correct
(c) Not correct
(d) Not correct
(e) Not correct

Explanation:

Developmental dysplasia of hip is more common in females.
Diffuse idiopathic skeletal hyperostosis is seen in over 50 years of age.
Fibrous dysplasia presents at peak incidence of 3-15 years. 75% are seen below 30 years of age.
Ankylosing spondylitis is more common in caucasians, with a caucasian: black ratio of 3:1.

Question 59

27. Which of the following are correct regarding hyperparathyroidism (HPT): (T/F)

(a) Brown tumours occur more frequently in secondary HPT.

(b) Rugger Jersey spine occurs more frequently in primary HPT.

(c) Increased incidence of slipped upper femoral epiphysis is associated with HPT.

(d) Chondrocalcinosis is seen in 15-20 %.

(e) A normal bone scan in about 80 %.

Answer 59

Answers:

(a) Not correct
(b) Not correct
(c) Correct
(d) Correct
(e) Correct

Explanation:

Brown tumours occur more frequently in primary hyperparathyroidism and Rugger Jersey spine is seen more frequently in secondary hyperparathyroidism.

Question 60

29. Which of the following are correct features of Paget’s disease: (T/F)

(a) Thickening of ileopectineal line.

(b) Pelvis is most commonly affected.

(c) Increased density of vertebra – ‘ivory vertebra’.

(d) Candle flame lysis.

(e) Sarcomatous transformation in 10-15 %.

Answer 60

Answers:

(a) Correct
(b) Correct
(c) Correct
(d) Correct
(e) Not correct

Explanation:

Paget’s disease of bone is a common, chronic bone disorder characterised by excessive abnormal bone remodelling. It frequently affects the pelvis, spine, skull and proximal long bones. It is relatively common and can affect up to 4% of individuals over 40 and up to 11% over the age of 80. Sarcomatous transformation is approximately 1%.