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Bone Tumors MCQs

Practice Set 47 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 921

Topic: Bone Tumors
A 9-year-old girl is found to have a "shepherd's crook" deformity of her proximal femur, café-au-lait spots with irregular "coast of Maine" borders, and precocious puberty. What is the underlying genetic mutation responsible for this triad?
. EXT1 mutation
. FGFR3 mutation
. GNAS1 somatic mutation
. COL1A1 mutation
. Runx2 mutation

Correct Answer & Explanation

. GNAS1 somatic mutation

Explanation

The clinical presentation is classic for McCune-Albright syndrome, which consists of polyostotic fibrous dysplasia, café-au-lait macules, and endocrine abnormalities. It is caused by a somatic, post-zygotic activating mutation in the GNAS1 gene.

Question 922

Topic: Bone Tumors

A 16-year-old boy has an osteoid osteoma of the proximal tibia confirmed by imaging.

He has failed conservative management with NSAIDs. What is the current gold standard minimally invasive treatment for this lesion?

. Intralesional steroid injection
. Radiofrequency ablation (RFA)
. Cryotherapy
. Curettage and bone grafting
. En bloc resection

Correct Answer & Explanation

. Radiofrequency ablation (RFA)

Explanation

Radiofrequency ablation (RFA) under CT guidance has become the gold standard treatment for osteoid osteoma when medical management fails. It offers a high success rate, minimal morbidity, and rapid recovery compared to open surgical excision.

Question 923

Topic: Bone Tumors

A 20-year-old man underwent excision of a small bone lesion causing severe night pain.

Which of the following substances is produced in excess by the nidus, explaining the dramatic response to aspirin?

. Serotonin
. Prostaglandin E2 (PGE2)
. Histamine
. Substance P
. Interleukin-1

Correct Answer & Explanation

. Prostaglandin E2 (PGE2)

Explanation

The nidus of an osteoid osteoma produces high levels of Prostaglandin E2 (PGE2) due to increased COX-2 expression. This mediates the intense pain and explains the characteristic relief provided by NSAIDs and aspirin.

Question 924

Topic: Bone Tumors

A 16-year-old male complains of severe right thigh pain that is worse at night and dramatically relieved by ibuprofen. Radiographs show a 7 mm radiolucent nidus surrounded by dense reactive sclerosis in the proximal femoral diaphysis. What is the most appropriate initial definitive management if medical therapy fails or is not tolerated?

. En bloc resection
. Curettage and bone grafting
. Radiofrequency ablation
. Radiation therapy
. Chemotherapy

Correct Answer & Explanation

. Radiofrequency ablation

Explanation

Correct Answer: Radiofrequency ablationThe presentation is classic for an osteoid osteoma. The lesion produces high levels of prostaglandins, which explains the dramatic relief with NSAIDs. If medical management fails, is not tolerated, or the patient prefers definitive treatment, percutaneous radiofrequency ablation (RFA) is the treatment of choice. It offers high success rates with significantly less morbidity compared to open surgical resection (en bloc or curettage).

Question 925

Topic: Bone Tumors

A 14-year-old boy presents with a painful scoliosis. Radiographs reveal a right-thoracic scoliotic curve. Advanced imaging shows a 1 cm radiolucent nidus with surrounding sclerosis in the T8 vertebra. Which of the following best describes the most likely location of the lesion and its relationship to the scoliotic curve?

. Vertebral body, on the convexity of the curve
. Vertebral body, on the concavity of the curve
. Posterior elements, on the convexity of the curve
. Posterior elements, on the concavity of the curve
. Intervertebral disc space, directly at the apex

Correct Answer & Explanation

. Posterior elements, on the concavity of the curve

Explanation

Osteoid osteomas of the spine typically arise in the posterior elements (pedicle or lamina). They cause asymmetric muscle spasm, leading to a painful scoliosis with the lesion classically located on the concavity of the curve.

Question 926

Topic: Bone Tumors

A 9-year-old girl presents with a limp, precocious puberty, and large irregular cafe-au-lait spots on her torso. Radiographs show a 'ground-glass' expansile lesion in her proximal femur with a 'shepherd's crook' deformity. What is the underlying pathophysiology of her bony lesions?

. Inhibiting mutation in the FGFR3 receptor
. Activating mutation in the GNAS1 gene affecting cAMP signaling
. Defect in the carbonic anhydrase II enzyme
. Mutation in the EXT1 gene affecting heparan sulfate
. Defective lysosomal storage of glycosaminoglycans

Correct Answer & Explanation

. Activating mutation in the GNAS1 gene affecting cAMP signaling

Explanation

McCune-Albright syndrome is characterized by polyostotic fibrous dysplasia, cafe-au-lait spots, and endocrinopathies. It is caused by a post-zygotic activating somatic mutation in the GNAS1 gene, resulting in continuous cAMP production.

Question 927

Topic: Bone Tumors

A 16-year-old male complains of nocturnal anterior thigh pain that is completely relieved by ibuprofen. Imaging shows a 1 cm radiolucent nidus with intense surrounding reactive sclerosis in the medial femoral diaphysis. What is the preferred minimally invasive definitive treatment?

. En bloc resection with wide margins
. Radiofrequency ablation
. Observation with scheduled oral NSAIDs
. External beam radiation therapy
. Intralesional corticosteroid injection

Correct Answer & Explanation

. Radiofrequency ablation

Explanation

Osteoid osteomas typically present with night pain relieved by NSAIDs and demonstrate a characteristic radiolucent nidus smaller than 1.5 cm. CT-guided radiofrequency ablation (RFA) is the current standard of care for definitive, minimally invasive treatment.

Question 928

Topic: Bone Tumors

A 16-year-old boy presents with aching pain in his right anterior tibia that worsens at night. The pain is completely relieved by ibuprofen. A CT scan reveals a 0.8 cm radiolucent nidus surrounded by dense sclerotic bone. The intense pain experienced by this patient is primarily mediated by high local concentrations of which substance?

. Histamine
. Bradykinin
. Prostaglandin E2
. Substance P
. Leukotriene B4

Correct Answer & Explanation

. Prostaglandin E2

Explanation

Osteoid osteomas secrete high levels of prostaglandins, particularly PGE2, which cause intense local vasodilation and pain, classically at night. This is why the pain is typically highly responsive to NSAIDs.

Question 929

Topic: Bone Tumors
A 9-year-old girl is evaluated for a leg length discrepancy and a limp. Radiographs demonstrate a "shepherd's crook" deformity of the proximal femur with a "ground-glass" appearance in the medullary canal. Physical examination reveals large café-au-lait spots with irregular borders. Which of the following genetic alterations is responsible for this condition?
. Activating missense mutation in the GNAS gene
. Loss-of-function mutation in the NF1 gene
. Mutation in the RUNX2 transcription factor
. Defect in the PTEN tumor suppressor gene
. Translocation t(11;22)

Correct Answer & Explanation

. Activating missense mutation in the GNAS gene

Explanation

The patient has McCune-Albright syndrome, characterized by polyostotic fibrous dysplasia, café-au-lait spots (coast of Maine), and endocrine abnormalities. It is caused by an activating post-zygotic somatic missense mutation in the GNAS gene, leading to increased cAMP.

Question 930

Topic: Bone Tumors

Which of the following secondary lesions is most frequently associated with a chondroblastoma?

. Osteoid osteoma
. Aneurysmal bone cyst
. Unicameral bone cyst
. Non-ossifying fibroma
. Osteosarcoma

Correct Answer & Explanation

. Aneurysmal bone cyst

Explanation

Approximately 15% to 20% of chondroblastomas are associated with a secondary aneurysmal bone cyst (ABC). Recognition of both components is critical to ensure thorough curettage and minimize the risk of recurrence.

Question 931

Topic: Bone Tumors

A 16-year-old male presents with right knee pain. Radiographs show a lytic, well-circumscribed lesion in the proximal tibial epiphysis. MRI demonstrates fluid-fluid levels within the lesion.

Biopsy confirms sheets of mononuclear cells with grooved nuclei. Which of the following is the most likely diagnosis?

. Giant cell tumor of bone
. Chondroblastoma with secondary aneurysmal bone cyst
. Clear cell chondrosarcoma
. Telangiectatic osteosarcoma
. Primary aneurysmal bone cyst

Correct Answer & Explanation

. Chondroblastoma with secondary aneurysmal bone cyst

Explanation

Chondroblastoma typically presents as an epiphyseal lytic lesion in young patients. Secondary aneurysmal bone cysts (ABCs), characterized by fluid-fluid levels on MRI, occur in up to 20-30% of chondroblastomas.

Question 932

Topic: Bone Tumors

A 9-year-old boy presents with chronic ankle pain and stiffness. The MRI and CT scans of his hindfoot are provided below. Based on the imaging findings demonstrating a lesion arising from the epiphysis, what is the most likely histological diagnosis of this mass?




. Chondroblastoma
. Osteoid osteoma
. Histologically identical to osteochondroma
. Giant cell tumor
. Aneurysmal bone cyst

Correct Answer & Explanation

. Histologically identical to osteochondroma

Explanation

Correct Answer: CThe imaging shows Dysplasia Epiphysealis Hemimelica (DEH) localized on the lateral side of the talus. Histologically, DEH is identical to an osteochondroma. The key distinguishing feature is its location: DEH arises from the epiphysis, whereas a classic osteochondroma arises from the metaphysis or diaphysis.

Question 933

Topic: Bone Tumors

A 5-year-old boy is being evaluated for a hard, asymmetrical mass around his knee. Radiographs are obtained. Which of the following radiographic findings is most characteristic of Dysplasia Epiphysealis Hemimelica?

. A well-defined lytic lesion with a sclerotic margin in the metaphysis
. Asymmetric epiphyseal enlargement with multiple ossification centers
. A 'sunburst' periosteal reaction
. A pedunculated bony outgrowth pointing away from the joint originating from the diaphysis
. Diffuse osteopenia with cortical thinning

Correct Answer & Explanation

. Asymmetric epiphyseal enlargement with multiple ossification centers

Explanation

Correct Answer: BOn radiographs, DEH characteristically shows asymmetric epiphyseal enlargement with multiple ossification centers. This reflects the abnormal, hemimelic overgrowth of the epiphyseal cartilage and its subsequent irregular ossification.

Question 934

Topic: Bone Tumors

A 7-year-old boy presents with the clinical finding shown below. Radiographs reveal an underlying epiphyseal lesion. Histological examination of this mass would most likely reveal features identical to which of the following conditions?



. Osteoid osteoma
. Osteochondroma
. Chondroblastoma
. Enchondroma
. Osteosarcoma

Correct Answer & Explanation

. Osteochondroma

Explanation

Correct Answer: OsteochondromaThe image shows a moderate, bone-hard swelling typical of Dysplasia Epiphysealis Hemimelica (DEH). Histologically, DEH is indistinguishable from an osteochondroma, featuring a cartilage cap with underlying trabecular bone. The key difference is anatomical location: DEH arises from the epiphysis, whereas osteochondromas arise from the metaphysis or diaphysis.

Question 935

Topic: Bone Tumors

The sagittal MRI provided demonstrates a mass protruding from the distal femoral epiphysis into the popliteal fossa. In the context of Dysplasia Epiphysealis Hemimelica, what is the fundamental etiology of this condition?



. Autosomal dominant mutation in the EXT1 gene
. Post-traumatic physeal arrest
. Unknown etiology
. Chronic repetitive microtrauma
. Intrauterine viral infection

Correct Answer & Explanation

. Unknown etiology

Explanation

Correct Answer: Unknown etiologyDespite its histological similarity to osteochondromas (which can be linked to EXT1/EXT2 mutations in multiple hereditary exostoses), the etiology of Dysplasia Epiphysealis Hemimelica (DEH) remains unknown.

Question 936

Topic: Bone Tumors

A 7-year-old boy presents with the clinical finding shown below. Palpation reveals a painless, bone-hard swelling. Based on the most likely diagnosis, what is the histological appearance of this lesion most similar to?




. Chondroblastoma
. Osteoid osteoma
. Osteochondroma
. Enchondroma
. Osteosarcoma

Correct Answer & Explanation

. Osteochondroma

Explanation

Correct Answer: OsteochondromaThe clinical image demonstrates a bone-hard swelling on the lateral side of the ankle, characteristic of Dysplasia Epiphysealis Hemimelica (DEH). Histologically, DEH is identical to an osteochondroma. The key differentiating factor is its anatomical origin: DEH arises from the epiphysis, whereas a classic osteochondroma arises from the metaphysis or diaphysis.

Question 937

Topic: Bone Tumors

A 10-year-old male presents with aching pain and limited knee range of motion. The lateral radiograph and sagittal MRI are shown below. The mass protrudes into the popliteal fossa. From which specific anatomical region does this pathology primarily arise?




. Diaphysis
. Metaphysis
. Physis (growth plate) strictly
. Epiphysis
. Articular cartilage only

Correct Answer & Explanation

. Epiphysis

Explanation

Correct Answer: EpiphysisThe images demonstrate Dysplasia Epiphysealis Hemimelica (DEH) of the knee. Unlike osteochondromas which arise from the metaphysis, DEH is a developmental disorder that specifically arises from the epiphysis, leading to asymmetric epiphyseal overgrowth and joint deformity.

Question 938

Topic: Bone Tumors

When evaluating a child with suspected Dysplasia Epiphysealis Hemimelica (DEH), what is the classic radiographic hallmark observed in the affected joint?

. Symmetric epiphyseal enlargement with a single central ossification center
. Asymmetric epiphyseal enlargement with multiple ossification centers
. Metaphyseal flaring with an 'Erlenmeyer flask' deformity
. Diaphyseal cortical thickening with a radiolucent nidus
. Punctate calcifications within the medullary canal of the diaphysis

Correct Answer & Explanation

. Asymmetric epiphyseal enlargement with multiple ossification centers

Explanation

Correct Answer: Asymmetric epiphyseal enlargement with multiple ossification centersOn radiographs, DEH characteristically presents as asymmetric epiphyseal enlargement (due to its hemimelic nature) accompanied by multiple ossification centers within the affected epiphyseal region.

Question 939

Topic: Bone Tumors

The imaging below shows a lesion localized on the lateral side of the talus. Histologically, this lesion is identical to an osteochondroma. What is the primary anatomical difference between this condition and a classic osteochondroma?


. This lesion arises from the diaphysis
. This lesion arises from the metaphysis
. This lesion arises from the epiphysis
. This lesion arises from the articular cartilage only
. This lesion arises from the joint capsule

Correct Answer & Explanation

. This lesion arises from the epiphysis

Explanation

Correct Answer: This lesion arises from the epiphysisThe imaging shows Dysplasia Epiphysealis Hemimelica (DEH) of the talus. Histologically, DEH is similar to an osteochondroma. However, the key distinguishing feature is that an osteochondroma arises from the metaphysis or diaphysis, whereas DEH arises directly from the epiphysis.

Question 940

Topic: Bone Tumors

Dysplasia epiphysealis hemimelica (DEH) is characterized by asymmetric overgrowth. Which of the following best describes the typical radiographic appearance of DEH?

. Symmetrical epiphyseal enlargement with a single central ossification center
. Asymmetric epiphyseal enlargement with multiple ossification centers
. Metaphyseal flaring with a sunburst periosteal reaction
. Diaphyseal cortical thickening with a nidus
. Epiphyseal destruction with joint space narrowing

Correct Answer & Explanation

. Asymmetric epiphyseal enlargement with multiple ossification centers

Explanation

Correct Answer: Asymmetric epiphyseal enlargement with multiple ossification centersCharacteristically, DEH lesions show on radiographs as asymmetric epiphyseal enlargement with multiple ossification centers. This reflects the irregular, hemimelic overgrowth of the affected epiphysis.

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