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Bone Tumors MCQs

Practice Set 46 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 901

Topic: Bone Tumors
A patient with suspected McCune-Albright syndrome exhibits a characteristic café-au-lait spot. How does the macroscopic appearance of this cutaneous lesion typically differ from those seen in Neurofibromatosis type 1 (NF1)?
. They are significantly smaller and more numerous
. They have irregular, jagged borders resembling the coast of Maine
. They are raised and palpable
. They exclusively cross the midline of the body
. They exhibit a smooth, coast of California border

Correct Answer & Explanation

. They have irregular, jagged borders resembling the coast of Maine

Explanation

Café-au-lait spots in McCune-Albright syndrome typically have irregular, jagged borders commonly described as the coast of Maine. In contrast, the lesions in NF1 have smooth borders referred to as the coast of California.

Question 902

Topic: Bone Tumors

Which of the following MRI findings is highly characteristic, though not entirely specific, for an aneurysmal bone cyst?

. Ground-glass matrix
. Popcorn calcifications
. Fluid-fluid levels
. Intramedullary target sign
. Double-line sign

Correct Answer & Explanation

. Fluid-fluid levels

Explanation

Fluid-fluid levels on MRI represent separated blood components of different densities. While highly characteristic of ABCs, they are not pathognomonic and can also be seen in telangiectatic osteosarcoma and giant cell tumors.

Question 903

Topic: Bone Tumors
A 7-year-old girl presents with a limp, irregular café-au-lait spots on her trunk, and a history of early vaginal bleeding. Pelvic radiographs show a lytic ground-glass lesion in the proximal femur. Which endocrine abnormality is most characteristic of this syndrome?
. Precocious puberty
. Hypothyroidism
. Adrenal insufficiency
. Hypoparathyroidism
. Type 1 Diabetes mellitus

Correct Answer & Explanation

. Precocious puberty

Explanation

McCune-Albright syndrome is characterized by the classic triad of polyostotic fibrous dysplasia, café-au-lait macules with "coast of Maine" irregular borders, and hyperfunctioning endocrinopathies, most commonly precocious puberty.

Question 904

Topic: Bone Tumors

A 25-year-old man with fibrous dysplasia presents with severe varus deformity of the proximal femur (shepherd's crook) and an impending fracture. Following a corrective valgus osteotomy, which is the most appropriate fixation method?

. Cortical bone grafting alone
. Plate and screw construct
. Intramedullary nailing
. External fixation
. Cancellous allograft packing

Correct Answer & Explanation

. Intramedullary nailing

Explanation

Intramedullary nailing is the preferred fixation method for shepherd's crook deformities in fibrous dysplasia. Plates and screws have a high failure rate due to poor screw purchase in dysplastic bone, and cortical bone grafts are rapidly resorbed by the disease process.

Question 905

Topic: Bone Tumors

Telangiectatic osteosarcoma can closely mimic an aneurysmal bone cyst on standard MRI. Which histologic feature best differentiates telangiectatic osteosarcoma from a primary ABC?

. Presence of multinucleated giant cells
. Fibrous septa separating blood-filled spaces
. Cytologic atypia of the septal stromal cells
. Presence of hemosiderin-laden macrophages
. Reactive woven bone formation

Correct Answer & Explanation

. Cytologic atypia of the septal stromal cells

Explanation

While both lesions show blood-filled cystic spaces separated by septa, telangiectatic osteosarcoma exhibits marked cytologic atypia, pleomorphism, and atypical mitoses within the septal stromal cells. The fibroblasts in an ABC are inherently benign.

Question 906

Topic: Bone Tumors

On a standard plain radiograph, fibrous dysplasia typically presents with which of the following classic morphologic appearances?

. Sunburst periosteal reaction with a Codman triangle
. "Onion-skin" periostitis
. Expansile medullary lesion with a "ground-glass" matrix
. Epiphyseal lytic lesion with a thick sclerotic rim
. Dense blastic lesion with a central radiolucent nidus

Correct Answer & Explanation

. Expansile medullary lesion with a "ground-glass" matrix

Explanation

Fibrous dysplasia typically appears as a radiolucent, expansile medullary lesion with a hazy, "ground-glass" matrix. This radiographic appearance directly reflects the histologic replacement of normal cancellous bone by abnormal fibrous tissue and irregular woven bone trabeculae.

Question 907

Topic: Bone Tumors
A 9-year-old girl is found to have polyostotic fibrous dysplasia, café-au-lait spots with irregular borders, and precocious puberty. Which of the following is true regarding surgical management of impending fractures in this patient?
. Cortical bone autograft is preferred over allograft
. Plate and screw constructs provide the lowest failure rates
. Intramedullary devices should be used to bypass the entire diseased segment
. Curettage and isolated bone grafting is the treatment of choice
. Surgical intervention is contraindicated until skeletal maturity

Correct Answer & Explanation

. Intramedullary devices should be used to bypass the entire diseased segment

Explanation

Patients with McCune-Albright syndrome have polyostotic fibrous dysplasia, which produces structurally weak bone. Fixation requires load-sharing intramedullary devices spanning the entire lesion; plates/screws and isolated autografts have unacceptably high failure rates due to bone resorption.

Question 908

Topic: Bone Tumors

A 45-year-old woman with known polyostotic fibrous dysplasia presents with new, painless soft tissue masses in her thigh musculature. MRI confirms well-circumscribed intramuscular myxomas. What is this specific clinical association called?

. Mazabraud syndrome
. McCune-Albright syndrome
. Ollier disease
. Maffucci syndrome
. Jaffe-Campanacci syndrome

Correct Answer & Explanation

. Mazabraud syndrome

Explanation

Mazabraud syndrome is a rare disorder characterized by the association of polyostotic fibrous dysplasia with single or multiple intramuscular myxomas. These myxomas are benign but are frequently located in the same anatomic region as the severely affected bones.

Question 909

Topic: Bone Tumors

A biopsy of a metaphyseal bone lesion shows irregular, curvilinear trabeculae of woven bone lacking osteoblastic rimming, set within a moderately cellular fibrous stroma. Radiographs show a "ground-glass" appearance. What is the most likely diagnosis?

. Aneurysmal bone cyst
. Osteosarcoma
. Non-ossifying fibroma
. Fibrous dysplasia
. Chondromyxoid fibroma

Correct Answer & Explanation

. Fibrous dysplasia

Explanation

The histologic description of "Chinese character" or "alphabet soup" trabeculae of woven bone without osteoblastic rimming in a fibrous stroma is the pathognomonic feature of fibrous dysplasia. This matches the classic radiographic "ground-glass" matrix.

Question 910

Topic: Bone Tumors

A 16-year-old boy presents with severe right anterior thigh pain that is predictably worse at night and dramatically relieved by NSAIDs. Imaging reveals the following characteristic finding.

What is the most characteristic biochemical feature of the central nidus in this lesion?

. High expression of alkaline phosphatase
. Excessive production of Prostaglandin E2
. Mutation in the EXT1 gene
. Translocation t(11;22)
. Elevated production of RANKL

Correct Answer & Explanation

. Excessive production of Prostaglandin E2

Explanation

Osteoid osteomas contain a central nidus that characteristically secretes high levels of Prostaglandin E2 (PGE2), causing nocturnal pain that responds to NSAIDs. The surrounding reactive sclerosis is a hallmark radiographic finding.

Question 911

Topic: Bone Tumors

A 13-year-old adolescent presents with a painful, rigid scoliotic curve. Imaging identifies a lesion with a radiolucent nidus on the concavity of the curve.

If surgical management is planned, what is the primary goal of the intervention?

. Spinal fusion across the scoliotic segment
. Complete en bloc resection of the involved vertebral body
. Excision or ablation of the nidus only
. Chemotherapy followed by intralesional curettage
. Radiation therapy to the affected pedicle

Correct Answer & Explanation

. Excision or ablation of the nidus only

Explanation

In spinal osteoid osteomas causing painful scoliosis, the lesion is typically found on the concavity. Successful excision or radiofrequency ablation of the nidus alone generally results in rapid relief of pain and spontaneous resolution of the scoliotic curve.

Question 912

Topic: Bone Tumors

A 15-year-old boy presents with progressive right thigh pain that is notably worse at night and rapidly relieved by ibuprofen. Imaging shows a cortical lesion with a central lucent nidus and surrounding sclerosis. What is the most appropriate definitive, minimally invasive treatment for this condition?

. En bloc wide resection
. Intralesional curettage and bone grafting
. Radiofrequency ablation (RFA)
. Adjuvant radiation therapy
. Neoadjuvant chemotherapy

Correct Answer & Explanation

. Radiofrequency ablation (RFA)

Explanation

The clinical and radiographic presentation is classic for an osteoid osteoma. Radiofrequency ablation (RFA) under CT guidance is the gold standard minimally invasive treatment, offering high success rates and minimal morbidity.

Question 913

Topic: Bone Tumors
A 9-year-old girl is evaluated for precocious puberty and a recent pathologic proximal femur fracture. Radiographs show a 'ground-glass' expansile lesion with a 'shepherd's crook' deformity. A post-zygotic somatic mutation in which of the following genes is responsible for this condition?
. GNAS1
. EXT1
. NF1
. FGFR3
. SH3BP2

Correct Answer & Explanation

. GNAS1

Explanation

The patient has McCune-Albright syndrome, characterized by polyostotic fibrous dysplasia, precocious puberty, and café-au-lait spots. This syndrome is caused by a somatic activating mutation in the GNAS1 gene, leading to increased cAMP.

Question 914

Topic: Bone Tumors

The radiograph demonstrates a typical osteoid osteoma. If a histopathologically identical lesion presented in the posterior elements of the spine, measured 3.0 cm in diameter, and caused progressive non-structural scoliosis without classic nocturnal pain, what would be the most likely diagnosis?

. Osteoid osteoma
. Osteosarcoma
. Osteoblastoma
. Aneurysmal bone cyst
. Chondroblastoma

Correct Answer & Explanation

. Osteoblastoma

Explanation

Osteoblastomas are histologically indistinguishable from osteoid osteomas but are distinguished clinically by their larger size (>2 cm), predilection for the posterior elements of the spine, and less predictable response to NSAIDs.

Question 915

Topic: Bone Tumors

A 15-year-old male presents with dull, aching thigh pain that is predictably worse at night and dramatically relieved by NSAIDs.

Based on the typical clinical and radiographic presentation shown, what is the most likely diagnosis?

. Ewing sarcoma
. Osteoid osteoma
. Chondroblastoma
. Osteoblastoma
. Non-ossifying fibroma

Correct Answer & Explanation

. Osteoid osteoma

Explanation

The classic presentation of night pain relieved by NSAIDs combined with an imaging finding of a radiolucent nidus surrounded by dense reactive sclerosis is diagnostic for osteoid osteoma. Prostaglandin production by the nidus is responsible for the characteristic pain pattern.

Question 916

Topic: Bone Tumors

An 11-year-old girl presents with fever, elevated ESR, and a painful thigh. Radiographs demonstrate a permeative, diaphyseal lytic lesion in the femur with a multilamellated ("onion skin") periosteal reaction. Cytogenetic testing reveals a t(11;22) translocation. Which fusion protein is produced by this translocation?

. EWS-FLI1
. SYT-SSX1
. PAX3-FOXO1
. TLS-CHOP
. BCR-ABL

Correct Answer & Explanation

. EWS-FLI1

Explanation

Ewing sarcoma is characterized by the t(11;22)(q24;q12) chromosomal translocation in >85% of cases. This results in the EWS-FLI1 fusion protein, which acts as an aberrant transcription factor driving oncogenesis.

Question 917

Topic: Bone Tumors

An 18-year-old male presents with persistent mid-thigh night pain that is reliably relieved by ibuprofen. Imaging shows a radiolucent nidus surrounded by reactive sclerosis.

If conservative management fails, what is the best next step in management?

. Amputation
. En bloc resection
. Radiofrequency ablation
. Curettage and bone grafting
. Primary radiation therapy

Correct Answer & Explanation

. Radiofrequency ablation

Explanation

Osteoid osteoma classically presents with night pain relieved by NSAIDs. Radiofrequency ablation is the gold standard minimally invasive surgical treatment when symptomatic management fails.

Question 918

Topic: Bone Tumors

A 22-year-old male undergoes excision of a cortical bone lesion in his proximal femur. Histology reveals a highly vascularized nidus of woven bone surrounded by sclerotic cortical bone.

The central nidus typically produces high levels of which substance?

. Interleukin-1
. Prostaglandin E2
. Tumor necrosis factor alpha
. Vascular endothelial growth factor
. Bone morphogenetic protein 2

Correct Answer & Explanation

. Prostaglandin E2

Explanation

Osteoid osteomas have a central nidus that produces high levels of Prostaglandin E2 (PGE2). This excess PGE2 production is the mechanism responsible for the intense local pain that is classically relieved by NSAIDs.

Question 919

Topic: Bone Tumors
A 65-year-old male presents with deep thigh pain. Radiographs reveal a lytic lesion in the proximal femur with endosteal scalloping >2/3 of cortical thickness and intralesional popcorn calcifications. What is the most appropriate definitive treatment for a conventional grade II lesion?
. Intralesional curettage and bone grafting
. Wide surgical resection
. Neoadjuvant chemotherapy followed by wide resection
. Primary radiation therapy
. Radiofrequency ablation

Correct Answer & Explanation

. Wide surgical resection

Explanation

Conventional high-grade (Grade II or III) chondrosarcomas are largely resistant to chemotherapy and radiation. Wide surgical resection is the mainstay of treatment to prevent local recurrence.

Question 920

Topic: Bone Tumors

A 14-year-old boy presents with worsening right thigh pain, typically at night, relieved by NSAIDs. An image is shown.

What is the classic radiolucent nidus size limit for this diagnosis?

. < 1.5 cm
. 1.5 - 3.0 cm
. > 3.0 cm
. > 5.0 cm
. > 10.0 cm

Correct Answer & Explanation

. < 1.5 cm

Explanation

Osteoid osteoma typically presents with nocturnal pain relieved by NSAIDs. The nidus is radiolucent and classically less than 1.5 cm in diameter. Lesions larger than this are considered osteoblastomas.

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