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Bone Tumors MCQs

Practice Set 1 of 52

This practice set contains high-yield board review questions covering key concepts in Bone Tumors. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 1

Topic: Bone Tumors

Which of the following is characteristic of osteosarcoma on imaging?

. Sunburst appearance
. Lytic lesion with sharp margins
. Purely sclerotic lesion
. Geographic destruction pattern
. Cortical thickening without periosteal reaction

Correct Answer & Explanation

. Sunburst appearance

Explanation

Osteosarcoma is often characterized by an aggressive periosteal reaction on X-ray, including a "sunburst" or "Codman's triangle" appearance, indicative of rapid bone formation and destruction.

Question 2

Topic: Bone Tumors

Which bone is most commonly affected by osteosarcoma in adolescents?

. Humerus
. Radius
. Vertebrae
. Fibula
. Femur

Correct Answer & Explanation

. Femur

Explanation

Osteosarcoma commonly affects the metaphysis of long bones, with the distal femur being the most frequent site, followed by the proximal tibia and proximal humerus.

Question 3

Topic: Bone Tumors

The differential diagnosis for patients presenting with radiographs consistent with myositis ossificans includes all of the following except:

. Osteosarcoma
. Osteochondroma
. Osteomyelitis
. C hondrosarcoma
. Rhabdomyosarcoma

Correct Answer & Explanation

. Rhabdomyosarcoma

Explanation

When evaluating a patient with calcification or ossification in abnormal regions, a thorough differential including all of the mentioned conditions should be considered. Osteochondromas will typically have an intramedullary canal continuous with the adjacent bone. Osteomyelitis will sometimes have associated constitutional symptoms. Osteosarcoma will typically have a radiodense center as opposed to the radiodense periphery of mature myositis ossificans. Chondrosarcoma can be confused with myositis ossificans.

Question 4

Topic: Bone Tumors

Typical histologic features of an osteoblastoma include all of the following except:

. Vascularized spindle cell stroma
. Nidus composed of haphazardly arranged network of osteoid trabeculae
. Occasional areas of aneurysmal bone cyst formation
. Osteoblasts rimming the trabeculae
. C hondrocytes arranged in a zonal pattern

Correct Answer & Explanation

. C hondrocytes arranged in a zonal pattern

Explanation

Histologically osteoblastoma is similar to an osteoid osteoma; its features include: Irregular osteoid arranged haphazardly with rimming by round osteoblasts Loose fibrovascular connective tissue between trabeculae Osteoblasts rimming the trabeculae Vascularized spindle cell stroma Areas of aneurysmal bone cyst formation can be seen

Question 5

Topic: Bone Tumors

A 22-year-old male presents with chronic, dull back pain that is not relieved by NSAIDs. Imaging reveals a 3.5 cm expansile radiolucent lesion in the posterior elements of L3. What is the most likely diagnosis?

. Osteoid osteoma
. Osteoblastoma
. Aneurysmal bone cyst
. Giant cell tumor
. Chordoma

Correct Answer & Explanation

. Osteoblastoma

Explanation

Osteoblastomas are typically larger than 2 cm and usually occur in the posterior elements of the spine. Unlike osteoid osteomas, the pain is less likely to be strictly nocturnal and is poorly relieved by NSAIDs.

Question 6

Topic: Bone Tumors

Secondary aneurysmal bone cysts (ABCs) are most frequently associated with which of the following underlying primary bone tumors?

. Osteosarcoma
. Osteochondroma
. Osteoblastoma
. Enchondroma
. Multiple myeloma

Correct Answer & Explanation

. Osteoblastoma

Explanation

Secondary ABCs can develop in the setting of other primary bone tumors, most notably giant cell tumors, chondroblastomas, and osteoblastomas. Identifying the underlying precursor lesion is critical for appropriate surgical management.

Question 7

Topic: Bone Tumors

A 65-year-old male presents with a pathologic compression fracture of L4. Laboratory tests show a monoclonal gammopathy. Which imaging modality is least likely to show increased uptake in the affected vertebra?

. MRI with gadolinium
. FDG-PET scan
. Technetium-99m bone scan
. CT scan with contrast
. Sestamibi scan

Correct Answer & Explanation

. Technetium-99m bone scan

Explanation

Multiple myeloma and solitary plasmacytoma are characterized by purely osteolytic lesions with minimal reactive bone formation. Consequently, a standard Technetium-99m bone scan is often falsely negative (cold).

Question 8

Topic: Bone Tumors

Primary aneurysmal bone cysts (ABCs) are neoplastic lesions driven by a specific genetic translocation. Which of the following genes is typically rearranged in primary ABCs?

. EXT1
. USP6
. GNAS
. RUNX2
. EWSR1

Correct Answer & Explanation

. USP6

Explanation

Primary ABCs are characterized by a t(16;17) translocation that causes upregulation of the USP6 gene. This true neoplastic nature distinguishes them from secondary ABCs, which lack this mutation.

Question 9

Topic: Bone Tumors

A 14-year-old girl has a large, expansile aneurysmal bone cyst in the posterior elements of C5 causing neck pain but no neurologic deficit. What is the most appropriate initial surgical management?

. En bloc vertebrectomy
. Preoperative embolization followed by extended curettage and bone grafting
. Primary radiotherapy
. Serial observation
. Denosumab therapy

Correct Answer & Explanation

. Preoperative embolization followed by extended curettage and bone grafting

Explanation

Preoperative embolization significantly reduces intraoperative blood loss for spinal ABCs. Extended intralesional curettage with high-speed burring and bone grafting achieves a low recurrence rate while preserving spinal stability.

Question 10

Topic: Bone Tumors

A 9-year-old girl is evaluated for a shepherd's crook deformity of the proximal femur, multiple cafe-au-lait spots with irregular borders, and precocious puberty. Which of the following mutations is responsible for this condition?

. Post-zygotic activating mutation of the GNAS1 gene
. Germline mutation of the RB1 gene
. Inactivating mutation of the EXT1 gene
. Translocation t(11;22)
. Mutation in the FGFR3 gene

Correct Answer & Explanation

. Post-zygotic activating mutation of the GNAS1 gene

Explanation

The patient has McCune-Albright syndrome, characterized by polyostotic fibrous dysplasia, cafe-au-lait macules, and endocrine abnormalities. It is caused by a somatic, post-zygotic activating mutation in the GNAS1 gene leading to increased intracellular cAMP.

Question 11

Topic: Bone Tumors

Radiofrequency ablation (RFA) is the treatment of choice for most osteoid osteomas. In which of the following anatomical locations is RFA generally considered contraindicated or highest risk, frequently necessitating open surgical resection?

. Proximal femur neck
. Diaphysis of the tibia
. Posterior elements of the spine near the spinal cord
. Scaphoid bone
. Iliac wing

Correct Answer & Explanation

. Posterior elements of the spine near the spinal cord

Explanation

RFA relies on thermal necrosis to destroy the nidus. It is generally contraindicated or highly hazardous if the lesion is within 1 cm of critical structures like the spinal cord or major motor nerves, due to the high risk of thermal neural injury.

Question 12

Topic: Bone Tumors

A 14-year-old female presents with back pain and a lytic lesion involving the posterior elements of L3. An MRI shows multiple fluid-fluid levels. What is the most appropriate initial surgical management for a symptomatic, locally aggressive lesion?

. En bloc spondylectomy
. Intralesional curettage and bone grafting
. Preoperative embolization followed by intralesional excision
. Observation
. Primary radiation therapy

Correct Answer & Explanation

. Preoperative embolization followed by intralesional excision

Explanation

Aneurysmal bone cysts (ABCs) in the spine typically involve the posterior elements and show fluid-fluid levels on MRI. Due to their high vascularity, preoperative embolization followed by aggressive intralesional curettage is the standard treatment to minimize blood loss.

Question 13

Topic: Bone Tumors

A 12-year-old boy presents with painful thoracic scoliosis. Imaging reveals a 1.2 cm radiolucent nidus surrounded by reactive sclerosis in the right T8 pedicle. Which of the following best describes the relationship of the lesion to the spinal curve?

. The lesion is located at the apex on the concavity of the curve.
. The lesion is located at the apex on the convexity of the curve.
. The lesion is located at the lower end vertebra of the curve.
. The lesion causes a compensatory structural curve above the nidus.
. There is no consistent relationship between the lesion and the curve.

Correct Answer & Explanation

. The lesion is located at the apex on the concavity of the curve.

Explanation

In osteoid osteoma of the spine, asymmetric muscle spasms cause a functional scoliosis. The lesion is characteristically located at the apex of the curve on the concave side.

Question 14

Topic: Bone Tumors

A 55-year-old male is diagnosed with a primary conventional chondrosarcoma of the T10 vertebral body. What is the most appropriate definitive management?

. Palliative radiation therapy
. Chemotherapy followed by intralesional curettage
. En bloc wide resection
. Intralesional curettage and cementation
. Systemic targeted therapy with denosumab

Correct Answer & Explanation

. En bloc wide resection

Explanation

Conventional chondrosarcoma is highly resistant to both chemotherapy and radiation therapy. The only potential for cure or long-term disease-free survival is en bloc wide surgical resection with negative margins.

Question 15

Topic: Bone Tumors

A 68-year-old male presents with generalized bone pain and a lytic lesion in the L4 vertebral body. Laboratory testing reveals hypercalcemia, anemia, and renal insufficiency. Serum protein electrophoresis shows an M-spike. Which of the following is most likely to be elevated in the patient's urine?

. Hydroxyproline
. Bence Jones proteins
. Alkaline phosphatase
. Osteocalcin
. N-telopeptide

Correct Answer & Explanation

. Bence Jones proteins

Explanation

The patient's presentation (CRAB symptoms: hyperCalcemia, Renal insufficiency, Anemia, Bone lesions) is classic for multiple myeloma. Bence Jones proteins (free light chains) are typically elevated and found in the urine of these patients.

Question 16

Topic: Bone Tumors

Which of the following characteristics best differentiates an osteoblastoma from an osteoid osteoma?

. Presence of a radiolucent nidus
. Relief of pain with salicylates
. Lesion size greater than 2 cm and progressive growth
. Location in the posterior elements of the spine
. Histological presence of osteoid trabeculae lined by osteoblasts

Correct Answer & Explanation

. Lesion size greater than 2 cm and progressive growth

Explanation

Osteoblastoma and osteoid osteoma share similar histology. However, osteoblastomas are distinguished by being larger than 2 cm, having progressive rather than self-limiting growth, and typically exhibiting pain that is less responsive to NSAIDs.

Question 17

Topic: Bone Tumors

A 20-year-old male with multiple hereditary exostoses (MHE) presents with slowly progressive myelopathy. MRI shows a bony outcropping from the C2 lamina compressing the spinal cord. The cartilage cap thickness is 0.5 cm. What is the most likely diagnosis and appropriate management?

. Chondrosarcoma; requires en bloc resection
. Osteochondroma; requires simple excision and decompression
. Osteoblastoma; requires curettage and bone grafting
. Osteoid osteoma; requires radiofrequency ablation
. Chordoma; requires proton beam therapy

Correct Answer & Explanation

. Osteochondroma; requires simple excision and decompression

Explanation

Spinal osteochondromas can cause compressive myelopathy, especially in patients with MHE. A cartilage cap thickness of <1.5-2.0 cm in an adult suggests a benign lesion, and simple excision with decompression is the standard treatment.

Question 18

Topic: Bone Tumors

A 16-year-old male presents with a dull ache in his posterior neck. Radiographs show a 2.5 cm radiolucent lesion with a sclerotic rim in the C4 lamina. Histology shows interlacing woven bone trabeculae lined by a single layer of plump osteoblasts. What is the most likely diagnosis?

. Osteoid osteoma
. Osteoblastoma
. Aneurysmal bone cyst
. Osteosarcoma
. Giant cell tumor

Correct Answer & Explanation

. Osteoblastoma

Explanation

The clinical presentation, size (>2 cm), location in the posterior elements of the spine, and histology are characteristic of an osteoblastoma. Osteoid osteomas are histologically identical but are typically less than 1.5 to 2 cm in diameter.

Question 19

Topic: Bone Tumors

Radiofrequency ablation (RFA) is considered the treatment of choice for most osteoid osteomas. What is the generally accepted minimum safe distance from the spinal cord or nerve roots to prevent thermal injury during RFA?

. 2 mm
. 5 mm
. 10 mm
. 15 mm
. 20 mm

Correct Answer & Explanation

. 10 mm

Explanation

To safely perform RFA for spinal osteoid osteomas without damaging neural elements, the lesion should generally be at least 10 mm away from the spinal cord and nerve roots. Closer proximity significantly increases the risk of thermal neuropraxia or permanent damage.

Question 20

Topic: Bone Tumors

What is the primary pathophysiologic mechanism of pain generated by an osteoid osteoma?

. Mechanical instability of the cortex
. High levels of Prostaglandin E2 produced by the nidus
. Compression of adjacent peripheral nerves
. Release of inflammatory cytokines from local hemorrhage
. Rapid periosteal expansion

Correct Answer & Explanation

. High levels of Prostaglandin E2 produced by the nidus

Explanation

The nidus of an osteoid osteoma produces high levels of Prostaglandin E2 (PGE2), which causes severe, deep, aching pain. This is the physiologic basis for why NSAIDs and aspirin are highly effective at relieving the pain.

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