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Bone Tumors MCQs

Practice Set 27 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 521

Topic: Bone Tumors

A 68-year-old female presents with severe back pain and generalized fatigue. Laboratory workup reveals hypercalcemia and a monoclonal spike on serum protein electrophoresis. Radiographs demonstrate multiple punched-out lytic lesions in her skull and vertebral bodies. Which of the following urinary findings is most characteristic of her underlying diagnosis?

. Elevated alkaline phosphatase
. Tartrate-resistant acid phosphatase (TRAP)
. Bence Jones proteins
. Homogentisic acid
. Hydroxyproline

Correct Answer & Explanation

. Bence Jones proteins

Explanation

The patient's presentation is classic for multiple myeloma, the most common primary malignancy of bone in adults. Bence Jones proteins (free light chains) are typically found in the urine of these patients.

Question 522

Topic: Bone Tumors

A 15-year-old boy presents with severe right tibial pain that occurs predominantly at night and is dramatically relieved by NSAIDs. Imaging

reveals a cortical radiolucent nidus measuring 8 mm surrounded by dense reactive sclerosis. What is the most appropriate definitive minimally invasive treatment?

. Observation alone
. Radiofrequency ablation
. En bloc resection
. Core decompression
. Curettage and bone grafting

Correct Answer & Explanation

. Radiofrequency ablation

Explanation

The clinical presentation and imaging are classic for an osteoid osteoma (nidus <1.5 cm, nocturnal pain relieved by NSAIDs). Radiofrequency ablation (RFA) under CT guidance is the standard of care and the most appropriate minimally invasive definitive treatment, offering excellent success rates with minimal morbidity.

Question 523

Topic: Bone Tumors

A 19-year-old male complains of severe, localized thigh pain that occurs primarily at night and is dramatically relieved by aspirin. Radiographs demonstrate an area of dense cortical sclerosis with a 6 mm radiolucent nidus. The intense pain associated with this lesion is mediated primarily by the local production of:

. Interleukin-1 (IL-1)
. Tumor necrosis factor-alpha (TNF-a)
. Prostaglandin E2 (PGE2)
. Substance P
. Histamine

Correct Answer & Explanation

. Prostaglandin E2 (PGE2)

Explanation

The clinical presentation is classic for an osteoid osteoma. The nidus of an osteoid osteoma has a very high concentration of cyclooxygenase-2 (COX-2), which produces high levels of Prostaglandin E2 (PGE2). This massive localized PGE2 release is responsible for the intense pain, which explains why NSAIDs (which inhibit COX and thus PGE2 production) are highly effective in providing symptomatic relief.

Question 524

Topic: Bone Tumors

A 15-year-old male presents with persistent knee pain. Radiographs reveal a metaphyseal lesion in the distal femur with a "sunburst" periosteal reaction.

Which of the following genetic syndromes is most strongly associated with this primary bone malignancy?

. Li-Fraumeni syndrome
. Neurofibromatosis type 1
. Marfan syndrome
. McCune-Albright syndrome
. Multiple hereditary exostoses

Correct Answer & Explanation

. Li-Fraumeni syndrome

Explanation

Osteosarcoma is the most common primary bone malignancy in children and is characterized by a "sunburst" periosteal reaction. It is strongly associated with Li-Fraumeni syndrome (p53 mutation) and hereditary retinoblastoma (Rb mutation).

Question 525

Topic: Bone Tumors

Which of the following MRI findings is most indicative of a low-grade chondrosarcoma rather than an enchondroma in a long bone?

. Lobular high T2 signal
. Endosteal scalloping involving >2/3 of the cortical thickness
. Presence of intralesional calcifications
. Small size (<3 cm)
. Absence of surrounding soft tissue edema

Correct Answer & Explanation

. Endosteal scalloping involving >2/3 of the cortical thickness

Explanation

Endosteal scalloping of more than two-thirds of the cortical thickness, cortical breakthrough, and a soft-tissue mass are strongly suggestive of chondrosarcoma. Enchondromas rarely cause deep endosteal scalloping in long bones.

Question 526

Topic: Bone Tumors
A 20-year-old male presents with a painless mass over his proximal humerus. Imaging shows a surface lesion < 3 cm with a "saucerized" appearance of the underlying cortex and an intact sclerotic margin. What is the diagnosis?
. Periosteal osteosarcoma
. Osteochondroma
. Periosteal chondrosarcoma
. Periosteal chondroma
. Parosteal osteosarcoma

Correct Answer & Explanation

. Periosteal chondroma

Explanation

Periosteal chondromas are benign surface lesions typically presenting with saucerization of the underlying cortex and sclerotic margins. They must be differentiated from periosteal chondrosarcomas, which are usually larger and lack the sclerotic rim.

Question 527

Topic: Bone Tumors

Mutations in the isocitrate dehydrogenase 1 and 2 (IDH1/IDH2) genes are pathognomonic and most frequently associated with which of the following skeletal conditions?

. Multiple Hereditary Exostoses
. McCune-Albright syndrome
. Ollier disease and solitary enchondromas
. Osteogenesis imperfecta
. Neurofibromatosis type 1

Correct Answer & Explanation

. Ollier disease and solitary enchondromas

Explanation

IDH1 and IDH2 somatic mutations are heavily implicated in the pathogenesis of Ollier disease, Maffucci syndrome, and solitary enchondromas. They result in abnormal chondrocyte proliferation through oncometabolite accumulation.

Question 528

Topic: Bone Tumors

A 55-year-old male is diagnosed with a grade 2 conventional chondrosarcoma of the proximal femur. There is no evidence of metastasis. What is the mainstay of treatment?

. Radiation therapy alone
. Neoadjuvant chemotherapy followed by wide resection
. Wide surgical resection alone
. Intralesional curettage with cementation
. High-dose systemic chemotherapy

Correct Answer & Explanation

. Wide surgical resection alone

Explanation

Conventional chondrosarcomas are largely resistant to both chemotherapy and radiation. The mainstay of treatment for intermediate to high-grade lesions is wide surgical resection with negative margins.

Question 529

Topic: Bone Tumors

Mutations in the EXT1 and EXT2 genes, seen in multiple hereditary exostoses (MHE), lead to the impaired synthesis of which of the following?

. Hyaluronic acid
. Heparan sulfate
. Chondroitin sulfate
. Keratan sulfate
. Type II collagen

Correct Answer & Explanation

. Heparan sulfate

Explanation

EXT1 and EXT2 gene mutations affect the EXT-polymerase complex, leading to impaired synthesis of heparan sulfate. This disruption alters normal Indian hedgehog (Ihh) signaling at the growth plate, leading to osteochondroma formation.

Question 530

Topic: Bone Tumors

A 17-year-old boy presents with a firm mass on the surface of his proximal tibia. Imaging demonstrates a subperiosteal lesion causing saucerization of the outer cortex, bordered by solid reactive sclerosis.

There is no marrow invasion. What is the most likely diagnosis?

. Periosteal chondroma
. Parosteal osteosarcoma
. Osteoid osteoma
. Periosteal osteosarcoma
. Osteochondroma

Correct Answer & Explanation

. Periosteal chondroma

Explanation

Periosteal chondromas develop under the periosteum, characteristically eroding the underlying cortex (saucerization) while inducing a dense sclerotic margin. They lack the perpendicular "hair-on-end" periosteal reaction seen in periosteal osteosarcoma.

Question 531

Topic: Bone Tumors

The IDH1 and IDH2 mutations commonly found in central chondrosarcomas and enchondromatosis syndromes promote tumorigenesis by producing which of the following oncometabolites?

. Fumarate
. Succinate
. D-2-hydroxyglutarate (D-2-HG)
. Alpha-ketoglutarate
. Citrate

Correct Answer & Explanation

. D-2-hydroxyglutarate (D-2-HG)

Explanation

Mutant IDH1/2 enzymes gain a neomorphic activity that converts alpha-ketoglutarate into the oncometabolite D-2-hydroxyglutarate (D-2-HG). This leads to DNA hypermethylation and altered cellular differentiation.

Question 532

Topic: Bone Tumors

A 28-year-old male presents with a painless palpable mass over the proximal humerus. Radiographs show a small surface lesion causing cortical saucerization with a well-defined sclerotic margin.

What is the most likely diagnosis?

. Periosteal chondrosarcoma
. Periosteal chondroma
. Osteochondroma
. Parosteal osteosarcoma
. Chondromyxoid fibroma

Correct Answer & Explanation

. Periosteal chondroma

Explanation

Periosteal chondromas are benign surface lesions typically presenting with cortical saucerization and a thick sclerotic margin. Unlike periosteal chondrosarcomas, they are usually less than 3 cm in size and possess a well-defined, intact sclerotic rim.

Question 533

Topic: Bone Tumors

A 12-year-old boy presents with right knee pain. Radiographs reveal an eccentric, lytic surface lesion causing cortical scalloping on the proximal medial tibia without medullary extension.

What is the most likely diagnosis?

. Osteochondroma
. Periosteal chondroma
. Non-ossifying fibroma
. Chondromyxoid fibroma
. Periosteal osteosarcoma

Correct Answer & Explanation

. Periosteal chondroma

Explanation

Periosteal (juxtacortical) chondromas typically present as eccentric, surface lesions causing a well-defined cortical scalloping with sclerotic margins. They usually measure less than 3 cm and do not invade the medullary canal.

Question 534

Topic: Bone Tumors

A 16-year-old male is diagnosed with an osteoid osteoma of the proximal femur. Which of the following best describes the molecular etiology of his severe nocturnal pain?

. Overexpression of RANKL
. Production of interleukin-1 by osteoclasts
. High local production of Prostaglandin E2 (PGE2)
. Release of substance P from surrounding nerve roots
. Histamine release by mast cells in the nidus

Correct Answer & Explanation

. High local production of Prostaglandin E2 (PGE2)

Explanation

The severe nocturnal pain characteristic of osteoid osteoma is caused by high levels of prostaglandins, particularly PGE2, produced by the nidus. This is why the pain is classically and dramatically relieved by NSAIDs.

Question 535

Topic: Bone Tumors
A 15-year-old boy presents with a painless mass over the proximal humerus. Radiographs show a small (< 3 cm), cortically based lucent lesion with a sclerotic margin and cortical saucerization. What is the most likely diagnosis?
. Osteoid osteoma
. Periosteal chondrosarcoma
. Periosteal chondroma
. Non-ossifying fibroma
. Osteochondroma

Correct Answer & Explanation

. Periosteal chondroma

Explanation

Periosteal chondromas typically present in the second decade as small (< 3 cm) surface lesions with cortical saucerization and a sclerotic inner margin. Periosteal chondrosarcomas have a similar appearance but are generally larger (> 3 cm) and occur in older adults.

Question 536

Topic: Bone Tumors

A 22-year-old female presents with multiple hard bony protuberances and bluish soft-tissue nodules on her hands. Radiographs reveal multiple enchondromas. What is her lifetime risk of developing any malignancy?

. Less than 5%
. 10-15%
. 25-30%
. 50-60%
. Nearly 100%

Correct Answer & Explanation

. Nearly 100%

Explanation

This patient has Maffucci syndrome, characterized by multiple enchondromas and soft-tissue hemangiomas. Patients with Maffucci syndrome have a lifetime risk of developing ANY malignancy (including chondrosarcoma and visceral/brain malignancies) approaching 100%, which is higher than the risk in Ollier disease.

Question 537

Topic: Bone Tumors

A 35-year-old man presents with a hard mass on the distal femur. Imaging shows a 6 cm lobulated surface mass with dense ring-and-arc calcifications. The lesion is elevating the periosteum but the underlying cortex is intact without medullary involvement.

What radiographic feature most strongly differentiates this from a periosteal chondroma?

. Intact underlying cortex
. Presence of ring-and-arc calcification
. Lack of medullary involvement
. Size of the lesion > 3 cm
. Soft tissue extension

Correct Answer & Explanation

. Size of the lesion > 3 cm

Explanation

Periosteal chondromas and periosteal chondrosarcomas both occur on the bone surface with an intact cortex and absent medullary involvement. A primary differentiating factor is size; lesions greater than 3 cm are highly suspicious for periosteal chondrosarcoma.

Question 538

Topic: Bone Tumors

A 24-year-old female presents with a painless, eccentric, expansile metaphyseal lesion in her proximal tibia. Histopathology demonstrates a lobular architecture with stellate and spindle cells embedded in a myxoid background, with multinucleated giant cells clustered at the lobular peripheries. What is the most likely diagnosis?

. Non-ossifying fibroma
. Aneurysmal bone cyst
. Chondromyxoid fibroma
. Myxoid chondrosarcoma
. Chondroblastoma

Correct Answer & Explanation

. Chondromyxoid fibroma

Explanation

Chondromyxoid fibroma typically presents as an eccentric metaphyseal lesion in young adults. Its classic histology features lobules of myxoid tissue containing stellate cells, with giant cells localized at the periphery of these lobules.

Question 539

Topic: Bone Tumors

A 14-year-old boy with multiple hemangiomas and venous malformations is found to have multiple asymmetric cartilaginous lesions in his hands and long bones. He is diagnosed with Maffucci syndrome. Compared to Ollier disease, he is at an inherently higher risk for which of the following?

. Retinoblastoma
. Astrocytoma and gastrointestinal malignancies
. Multiple myeloma
. Osteosarcoma
. Thyroid carcinoma

Correct Answer & Explanation

. Astrocytoma and gastrointestinal malignancies

Explanation

Maffucci syndrome is characterized by multiple enchondromas and vascular malformations. In addition to a near 100% risk of chondrosarcoma, these patients have a significantly higher risk of extraskeletal malignancies, notably astrocytomas and GI tract carcinomas, compared to Ollier disease.

Question 540

Topic: Bone Tumors

A 15-year-old male presents with a symptomatic surface lesion on his proximal humerus.

Imaging displays a 2 cm lesion causing saucerization of the outer cortex, with an intact sclerotic rim and without medullary extension. Which feature most reliably differentiates this lesion from a periosteal osteosarcoma?

. Saucerization of the underlying cortex
. Intact sclerotic cortical margin without true medullary extension
. Presence of a 'sunburst' periosteal reaction
. Location in the metaphysis rather than the diaphysis
. Size greater than 5 cm

Correct Answer & Explanation

. Saucerization of the underlying cortex

Explanation

Periosteal chondromas typically cause a well-defined saucerization of the outer cortex with a thick sclerotic rim and do not invade the medullary canal. Periosteal osteosarcoma tends to be larger, lacks a well-defined sclerotic rim, and often exhibits aggressive periosteal reactions.

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