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Bone Tumors MCQs

Practice Set 26 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 501

Topic: Bone Tumors

A 14-year-old patient with polyostotic fibrous dysplasia presents with a progressive varus deformity of the proximal femur (Shepherd's crook deformity). What is the most appropriate surgical strategy to prevent recurrence?

. Isolated curettage and bone grafting with allograft
. Valgus osteotomy and fixation with a dynamic hip screw
. Valgus osteotomy and stabilization with an intramedullary nail
. External fixation with gradual distraction osteogenesis
. Observation until skeletal maturity

Correct Answer & Explanation

. Valgus osteotomy and stabilization with an intramedullary nail

Explanation

Correct Answer: CFor the Shepherd's crook deformity in Fibrous Dysplasia, the gold standard is a valgus-producing osteotomy to improve mechanical alignment, stabilized by an intramedullary device. Intramedullary nails are preferred over plates because they provide better support for the entire weakened diaphysis and are less likely to fail in the 'ground-glass' bone.

Question 502

Topic: Bone Tumors
A 9-year-old girl presents with a pathologic proximal femur fracture, precocious puberty, and large, irregular "coast of Maine" café-au-lait spots. The underlying pathophysiology involves which of the following?
. Inactivating mutation in the EXT1 gene
. Activating mutation of the GNAS gene increasing intracellular cAMP
. Mutation in the Gsa protein decreasing intracellular cAMP
. Chromosomal translocation t(11;22)
. Mutation in the RUNX2 gene

Correct Answer & Explanation

. Activating mutation of the GNAS gene increasing intracellular cAMP

Explanation

McCune-Albright syndrome is characterized by polyostotic fibrous dysplasia, endocrine abnormalities, and café-au-lait spots. It is caused by a somatic activating mutation in the GNAS gene, leading to elevated cAMP levels.

Question 503

Topic: Bone Tumors
A 9-year-old girl presents with precocious puberty, café-au-lait spots with irregular borders, and a "shepherd's crook" deformity of the proximal femur. Which of the following accurately describes the underlying molecular defect?
. Post-zygotic activating mutation in the GNAS1 gene
. Germline inactivating mutation in the EXT1 gene
. Germline mutation in the NF1 gene
. Post-zygotic mutation in the PIK3CA gene
. Inactivating mutation in the PTEN gene

Correct Answer & Explanation

. Post-zygotic activating mutation in the GNAS1 gene

Explanation

McCune-Albright syndrome is characterized by polyostotic fibrous dysplasia, café-au-lait spots (Coast of Maine), and endocrinopathies like precocious puberty. It is caused by a somatic (post-zygotic) activating mutation in the GNAS1 gene.

Question 504

Topic: Bone Tumors
A 9-year-old girl is diagnosed with McCune-Albright syndrome after presenting with polyostotic fibrous dysplasia, a large café-au-lait macule with irregular borders, and early breast development. The GNAS1 gene mutation in this disorder results in the overactivity of which of the following signaling pathways?
. Wnt/beta-catenin pathway
. Transforming growth factor-beta (TGF-beta) pathway
. cAMP generation via the Gs-alpha protein
. Receptor tyrosine kinase signaling
. MAP kinase signaling pathway

Correct Answer & Explanation

. cAMP generation via the Gs-alpha protein

Explanation

McCune-Albright syndrome is caused by a somatic activating mutation in the GNAS1 gene. This leads to constitutive activation of the Gs-alpha protein, resulting in unregulated overproduction of intracellular cAMP, which drives the endocrine and skeletal abnormalities.

Question 505

Topic: Bone Tumors
An 8-year-old girl with precocious puberty and large café-au-lait spots presents with a progressive 'shepherd's crook' deformity of the proximal femur. What is the most appropriate surgical management for this deformity?
. Curettage and autologous bone grafting
. Bisphosphonate therapy alone
. Valgus-producing osteotomy with intramedullary nailing
. Proximal femoral replacement
. Open reduction and internal fixation with a dynamic hip screw

Correct Answer & Explanation

. Valgus-producing osteotomy with intramedullary nailing

Explanation

The diagnosis is McCune-Albright syndrome (Fibrous Dysplasia). Lesions resorb bone grafts and often cause plate/screw failure; the gold standard is valgus-producing osteotomy stabilized with an intramedullary nail.

Question 506

Topic: Bone Tumors

A 5-year-old boy presents with a hard, painless swelling on the medial aspect of his right ankle, limiting range of motion. Radiographs show an irregular, lobulated bony mass arising exclusively from the medial epiphysis of the distal tibia. What is the most likely diagnosis?

. Osteochondroma
. Ollier disease
. Trevor disease (Dysplasia Epiphysealis Hemimelica)
. Chondrodysplasia punctata
. Melorheostosis

Correct Answer & Explanation

. Trevor disease (Dysplasia Epiphysealis Hemimelica)

Explanation

Trevor disease (Dysplasia Epiphysealis Hemimelica) is characterized by an asymmetric osteochondroma-like overgrowth arising from an epiphysis, most commonly affecting the ankle or knee in young children.

Question 507

Topic: Bone Tumors

A 35-year-old male with a history of X-linked recessive spondyloepiphyseal dysplasia tarda presents with worsening joint pain and stiffness in his hips and knees. Which of the following is a known long-term complication associated with this condition?

. Progressive arthropathy
. Osteosarcoma
. Recurrent pathological fractures
. Avascular necrosis of the scaphoid
. Charcot neuroarthropathy

Correct Answer & Explanation

. Progressive arthropathy

Explanation

Correct Answer: Progressive arthropathySpondyloepiphyseal dysplasia tarda (SEDt) is an osteochondrodysplasia that can be associated with progressive arthropathy, leading to significant joint pain and stiffness in adulthood.

Question 508

Topic: Bone Tumors

A patient undergoing chemotherapy for osteosarcoma develops neutropenia. This significantly increases their risk of bacterial infections. Which of the following is the predominant mechanism by which neutrophils combat bacterial pathogens?

. Producing large quantities of antibodies to neutralize bacteria.
. Presenting bacterial antigens to T lymphocytes.
. Phagocytosis, degranulation of antimicrobial substances, and formation of neutrophil extracellular traps (NETs).
. Secreting anti-inflammatory cytokines to dampen the immune response.
. Directly lysing infected host cells using perforin and granzymes.

Correct Answer & Explanation

. Phagocytosis, degranulation of antimicrobial substances, and formation of neutrophil extracellular traps (NETs).

Explanation

Neutrophils are the most abundant granulocytes and are crucial first responders to bacterial infections. Their primary mechanisms of action include: 1) Phagocytosis: engulfing and destroying bacteria; 2) Degranulation: releasing antimicrobial substances (e.g., defensins, lysozyme) from their granules into phagolysosomes or extracellularly; and 3) Formation of Neutrophil Extracellular Traps (NETs): releasing decondensed chromatin decorated with antimicrobial proteins to trap and kill pathogens. They do not primarily produce antibodies, present antigens, or directly lyse host cells.

Question 509

Topic: Bone Tumors

Which of the following pathologies is most commonly associated with a 'sunburst' or 'onion skin' appearance on plain radiographs?

. Osteosarcoma
. Ewing sarcoma
. Chondrosarcoma
. Osteochondroma
. Enchondroma

Correct Answer & Explanation

. Ewing sarcoma

Explanation

Ewing sarcoma is classically associated with an 'onion skin' or lamellated periosteal reaction due to its rapid growth and cyclical bone formation. It can also present with a 'sunburst' pattern, although the 'sunburst' pattern is more often described with osteosarcoma due to aggressive tumor spicules radiating from the cortex. Given the two options, Ewing sarcoma is strongly linked to the 'onion skin' appearance. Osteosarcoma typically presents with a 'sunburst' or Codman's triangle.

Question 510

Topic: Bone Tumors

What is the most common site for osteoid osteoma?

. Vertebrae
. Small bones of the hands and feet
. Proximal femur
. Distal tibia
. Skull

Correct Answer & Explanation

. Proximal femur

Explanation

The proximal femur is the most common site for osteoid osteoma, especially in the femoral neck. While it can occur in many bones, including the tibia and spine, the femur (proximal) is the most frequently affected long bone.

Question 511

Topic: Bone Tumors

Which of the following is a key distinguishing feature of osteosarcoma when compared to Ewing sarcoma on plain radiographs?

. The presence of a 'sunburst' pattern of periosteal reaction.
. A large soft tissue mass with layered 'onion skin' periosteal reaction.
. A geographic pattern of bone destruction.
. Permeative pattern of bone destruction.
. Central calcification within the lesion.

Correct Answer & Explanation

. The presence of a 'sunburst' pattern of periosteal reaction.

Explanation

Osteosarcoma (Option A) is classically associated with an aggressive periosteal reaction characterized by a 'sunburst' or 'spiculated' appearance, and Codman's triangle. Ewing sarcoma (Option B) is characterized by a large soft tissue mass and a layered 'onion skin' periosteal reaction. Geographic (Option C) and Permeative (Option D) patterns describe bone destruction but are less specific in distinguishing these two. Central calcification (Option E) can be seen in various bone lesions, including enchondromas or fibrous dysplasia, and is not a distinguishing feature of osteosarcoma over Ewing sarcoma. The 'sunburst' pattern is highly characteristic of osteosarcoma.

Question 512

Topic: Bone Tumors

What is the most common site of metastasis for osteosarcoma?

. Regional lymph nodes.
. Brain.
. Liver.
. Lungs.
. Spine.

Correct Answer & Explanation

. Lungs.

Explanation

The most common site of metastasis for osteosarcoma is the lungs (Option D). While osteosarcoma can metastasize to other sites, including bone (skip lesions), brain, and rarely lymph nodes, pulmonary metastases are overwhelmingly the most frequent and a critical prognostic factor. Therefore, thorough pulmonary staging is essential during the workup of osteosarcoma.

Question 513

Topic: Bone Tumors

A 22-year-old male has an osteoid osteoma of the proximal femur treated with radiofrequency ablation.

What is the most critical anatomical structure to protect during ablation if the lesion is located in the posterior aspect of the femoral neck?

. Femoral vein
. Obturator nerve
. Sciatic nerve
. Medial circumflex femoral artery
. Lateral femoral cutaneous nerve

Correct Answer & Explanation

. Medial circumflex femoral artery

Explanation

Radiofrequency ablation of posterior femoral neck lesions carries the risk of thermal injury to the medial circumflex femoral artery (MCFA), which could lead to avascular necrosis of the femoral head.

Question 514

Topic: Bone Tumors

A 14-year-old boy presents with progressive right thigh pain that is significantly worse at night and reliably relieved by ibuprofen. Radiographs reveal a cortical lesion with a central radiolucent nidus and surrounding reactive sclerosis.

What is the primary biochemical mediator responsible for this classic pain pattern?

. Tumor necrosis factor-alpha
. Interleukin-1 beta
. Prostaglandin E2
. Matrix metalloproteinase-9
. Substance P

Correct Answer & Explanation

. Prostaglandin E2

Explanation

Osteoid osteomas characteristically secrete high levels of Prostaglandin E2 (PGE2) from the nidus. This local PGE2 production causes intense vasodilation and nerve fiber sensitization, leading to night pain that is uniquely responsive to NSAIDs.

Question 515

Topic: Bone Tumors

A 19-year-old male is undergoing definitive, minimally invasive treatment for a functionally limiting osteoid osteoma in the proximal femur.

During CT-guided radiofrequency ablation (RFA), what is the optimal target temperature and duration to ensure destruction of the nidus?

. 50°C for 2 minutes
. 90°C for 5 to 6 minutes
. 120°C for 10 minutes
. -20°C for 5 minutes
. 60°C for 1 minute

Correct Answer & Explanation

. 90°C for 5 to 6 minutes

Explanation

Radiofrequency ablation uses a high-frequency alternating current to generate thermal coagulation. The standard successful protocol for an osteoid osteoma nidus targets a probe tip temperature of 90°C for approximately 5 to 6 minutes.

Question 516

Topic: Bone Tumors

An 18-year-old male presents with persistent right anterior thigh pain that worsens at night. He reports significant relief of symptoms within 30 minutes of taking ibuprofen. Radiographs and a subsequent CT scan demonstrate a 1 cm radiolucent nidus surrounded by dense sclerotic bone in the femoral diaphysis.

If the patient cannot tolerate long-term NSAID therapy, what is the most appropriate first-line definitive intervention?

. Wide en bloc resection
. CT-guided radiofrequency ablation (RFA)
. Intralesional curettage and prophylactic internal fixation
. External beam radiation therapy
. Neoadjuvant chemotherapy followed by marginal excision

Correct Answer & Explanation

. CT-guided radiofrequency ablation (RFA)

Explanation

CT-guided radiofrequency ablation (RFA) is the standard minimally invasive treatment for an osteoid osteoma when medical management fails or is poorly tolerated. It offers a high success rate with minimal morbidity compared to open surgical excision.

Question 517

Topic: Bone Tumors

A 16-year-old female presents with pain in her proximal tibia. MRI reveals an expansile, multiloculated lesion with prominent fluid-fluid levels. Genetic analysis confirms a translocation involving t(16;17). Which gene is upregulated as a result of this translocation?

. EWS
. FLI1
. GNAS
. H3F3A
. USP6

Correct Answer & Explanation

. USP6

Explanation

Aneurysmal bone cysts (ABCs) are benign, blood-filled, multiloculated lesions characterized by fluid-fluid levels on MRI. The primary variant is a true neoplasm driven by translocations causing the upregulation of the USP6 oncogene.

Question 518

Topic: Bone Tumors
A 7-year-old girl presents with precocious puberty, a large café-au-lait spot with irregular "coast of Maine" borders on her torso, and a limp. Radiographs show a "ground-glass" expansile lesion in her proximal femur. The somatic mutation responsible for this syndrome occurs in which of the following genes?
. NF1
. FGFR3
. COMP
. GNAS1
. SH3BP2

Correct Answer & Explanation

. GNAS1

Explanation

This patient has McCune-Albright Syndrome, characterized by polyostotic fibrous dysplasia, precocious puberty, and "coast of Maine" café-au-lait spots. It is caused by a post-zygotic activating somatic mutation in the GNAS1 gene, leading to increased cAMP.

Question 519

Topic: Bone Tumors

A 14-year-old male presents with a painful spinal deformity that is worse at night. Imaging reveals an osteoid osteoma in the right T10 lamina. Which of the following best describes the typical curve pattern and natural history of his scoliosis following definitive radiofrequency ablation of the nidus?

. Left-sided convexity that typically resolves post-ablation if present for less than 15 months.
. Right-sided convexity that typically resolves post-ablation if present for less than 15 months.
. Left-sided convexity that requires concomitant spinal fusion regardless of symptom duration.
. Right-sided convexity that typically progresses rapidly post-ablation.
. Structural scoliosis with significant vertebral body rotation requiring immediate bracing.

Correct Answer & Explanation

. Left-sided convexity that typically resolves post-ablation if present for less than 15 months.

Explanation

Osteoid osteoma in the spine causes painful scoliosis with the concavity directed toward the side of the lesion due to asymmetric muscle spasm. Ablation usually leads to complete curve resolution if the symptoms have been present for less than 15 months.

Question 520

Topic: Bone Tumors

In a patient with Neurofibromatosis Type 1, which skeletal manifestation is considered a characteristic diagnostic criterion?

. Anterolateral tibial bowing
. Posteromedial tibial bowing
. Polyostotic fibrous dysplasia
. Multiple osteochondromas
. Spondyloepiphyseal dysplasia

Correct Answer & Explanation

. Anterolateral tibial bowing

Explanation

Anterolateral tibial bowing (often progressing to congenital pseudarthrosis of the tibia) is a classic skeletal manifestation and a diagnostic criterion for NF1. Posteromedial bowing is typically associated with calcaneovalgus foot deformity and resolves spontaneously.

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