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Bone Tumors MCQs

Practice Set 5 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 81

Topic: Bone Tumors
A 10-year-old girl is evaluated for a limp. Radiographs demonstrate a "shepherd's crook" deformity of the proximal femur with a ground-glass appearance of the medullary canal. She also exhibits precocious puberty and irregular café-au-lait spots. What is the most likely diagnosis?
. Neurofibromatosis type 1
. McCune-Albright syndrome
. Jaffe-Campanacci syndrome
. Ollier disease
. Maffucci syndrome

Correct Answer & Explanation

. McCune-Albright syndrome

Explanation

McCune-Albright syndrome is a triad of polyostotic fibrous dysplasia (causing the ground-glass bone lesions and shepherd's crook deformity), café-au-lait spots with irregular "coast of Maine" borders, and endocrinopathies such as precocious puberty.

Question 82

Topic: Bone Tumors

Klippel-Trenaunay syndrome is characterized by cutaneous capillary venous malformation, varicose veins, and which of the following:

. Multiple enchondromas
. Multiple osteochondromas
. Limb hypertrophy
. Seizure disorder
. C ongenital pseudarthrosis of the tibia

Correct Answer & Explanation

. Limb hypertrophy

Explanation

Klippel-Trenaunay syndrome has three essential features: cutaneous capillary venous malformation, varicose veins, and hypertrophy of the involved limb in length and/or width. The syndrome usually presents before adolescence. The tissue abnormalities typically do not cross the midline, and the entire limb is not uniformly affected.

Question 83

Topic: Bone Tumors

A 65-year-old male presents with bone pain and a lytic lesion in his proximal femur. Laboratory studies reveal hypercalcemia and a monoclonal spike on serum protein electrophoresis. Which imaging modality is most appropriate to evaluate the extent of skeletal involvement?

. Technetium-99m bone scan
. Low-dose whole-body CT
. MRI of the affected femur only
. Indium-111 leukocyte scan
. Dexa scan

Correct Answer & Explanation

. Low-dose whole-body CT

Explanation

Low-dose whole-body CT or whole-body MRI are the preferred imaging modalities for assessing skeletal involvement in multiple myeloma. Technetium-99m bone scans are notoriously unreliable because myeloma lesions typically lack osteoblastic activity.

Question 84

Topic: Bone Tumors

The proximal humerus is the most common location of unicameral bone cysts. Which of the following is the second most common location:

. Distal radius
. Iliac wing
. Proximal femur
. Distal femur
. Proximal tibia

Correct Answer & Explanation

. Proximal femur

Explanation

The proximal femur is the second most common location for unicameral bone cysts. All other locations are distinctly less common.

Question 85

Topic: Bone Tumors

An 8-year old patient presents with pain in a unicameral bone cyst of the proximal femur. Which of the following treatments is most likely to prevent fracture:

. Intralesional steroid injection
. Intralesional bone marrow injection
. Intralesional injection of demineralized bone matrix
. C urettage and bone graft
. C urettage, bone graft, and internal fixation

Correct Answer & Explanation

. C urettage, bone graft, and internal fixation

Explanation

Injection of any substance has a risk of recurrence, even if the injection is repeated. Bone graft has a risk as well, but internal fixation decreases the risk of fracture.

Question 86

Topic: Bone Tumors

All of the following are common in McC une-Albright syndrome except:

. Precocious puberty
. Polyostotic fibrous dysplasia
. Cafu-au-lait spots
. Bowing of long bones
. Multiple osteocartilaginous exostoses

Correct Answer & Explanation

. Multiple osteocartilaginous exostoses

Explanation

McCune-Albright syndrome consists of polyostotic fibrous dysplasia, precocious puberty, and cafa-au-lait spots. Long bone deformity is almost universal. Multiple osteocartilaginous exostoses are not part of this syndrome.

Question 87

Topic: Bone Tumors

The classic nocturnal pain associated with an osteoid osteoma is primarily mediated by the high local concentration of which of the following substances?

. Histamine
. Prostaglandin E2
. Bradykinin
. Interleukin-1
. Tumor necrosis factor-alpha

Correct Answer & Explanation

. Prostaglandin E2

Explanation

Osteoid osteomas produce high levels of Prostaglandin E2 due to robust COX-2 expression within the nidus. This local PGE2 production explains the characteristic severe nocturnal pain and its dramatic relief with nonsteroidal anti-inflammatory drugs.

Question 88

Topic: Bone Tumors
A 12-year-old girl presents with a shepherd's crook deformity of the femur and café-au-lait spots with irregular borders. This condition is caused by a somatic mutation affecting which of the following genes?
. EXT1
. GNAS1
. NF1
. FGFR3
. SH3BP2

Correct Answer & Explanation

. GNAS1

Explanation

McCune-Albright syndrome, characterized by polyostotic fibrous dysplasia, endocrinopathy, and café-au-lait spots, is caused by a somatic activating mutation in the GNAS1 gene. This mutation impairs the GTPase activity of the alpha subunit of the Gs protein, leading to increased cAMP.

Question 89

Topic: Bone Tumors

A 65-year-old woman presents with back pain and generalized fatigue. Radiographs show multiple punched-out lytic lesions in her skull and pelvis. Laboratory tests show hypercalcemia and elevated creatinine. Which diagnostic test is most essential for confirming the underlying diagnosis?

. Serum alkaline phosphatase
. Serum protein electrophoresis
. Prostate-specific antigen level
. Thyroid stimulating hormone
. 24-hour urine cortisol

Correct Answer & Explanation

. Serum protein electrophoresis

Explanation

The clinical picture strongly suggests multiple myeloma, characterized by the CRAB criteria (HyperCalcemia, Renal failure, Anemia, Bone lesions). Serum protein electrophoresis (SPEP) is critical to identify the monoclonal M-protein spike associated with this plasma cell dyscrasia.

Question 90

Topic: Bone Tumors

Percutaneous CT-guided radiofrequency ablation (RFA) is currently considered the gold standard, first-line intervention for which of the following symptomatic lesions?

. Chondroblastoma
. Osteoid osteoma
. Enchondroma
. Aneurysmal bone cyst
. Osteoblastoma larger than 4 cm

Correct Answer & Explanation

. Osteoid osteoma

Explanation

CT-guided radiofrequency ablation (RFA) provides excellent clinical success rates for symptomatic osteoid osteomas. It has largely replaced traditional surgical en bloc resection due to lower morbidity and faster patient recovery.

Question 91

Topic: Bone Tumors

A 9-year-old girl is diagnosed with polyostotic fibrous dysplasia, precocious puberty, and cafe-au-lait spots. The pathophysiology of her condition is directly related to a mutation in which of the following?

. Gs-alpha protein (GNAS1 gene)
. Fibroblast growth factor receptor 3 (FGFR3)
. Collagen type I alpha 1 chain (COL1A1)
. EXT1 tumor suppressor gene
. Retinoblastoma (Rb) gene

Correct Answer & Explanation

. Gs-alpha protein (GNAS1 gene)

Explanation

McCune-Albright syndrome features polyostotic fibrous dysplasia, endocrine abnormalities, and cafe-au-lait spots. It is caused by a somatic, post-zygotic activating mutation in the GNAS1 gene, resulting in elevated intracellular cAMP.

Question 92

Topic: Bone Tumors

A 65-year-old man presents with a rapidly enlarging mass in his proximal femur. Radiographs demonstrate a pre-existing lesion with rings-and-arcs calcification and a new, large, aggressive unmineralized soft tissue mass. Which of the following is the most likely diagnosis?

. Clear cell chondrosarcoma
. Mesenchymal chondrosarcoma
. Dedifferentiated chondrosarcoma
. Secondary osteosarcoma
. Primary lymphoma of bone

Correct Answer & Explanation

. Dedifferentiated chondrosarcoma

Explanation

A bimorphic radiographic appearance (a low-grade cartilaginous lesion adjacent to a high-grade, unmineralized soft-tissue mass) is pathognomonic for dedifferentiated chondrosarcoma. This transformation carries a very poor prognosis.

Question 93

Topic: Bone Tumors

A 14-year-old male with multiple hereditary exostoses (MHE) is evaluated. The genetic mutation associated with his condition leads to a deficiency in the synthesis of which of the following?

. Hyaluronic acid
. Heparan sulfate
. Chondroitin sulfate
. Keratan sulfate
. Dermatan sulfate

Correct Answer & Explanation

. Heparan sulfate

Explanation

MHE is an autosomal dominant condition caused by mutations in the EXT1 or EXT2 genes. These genes encode glycosyltransferases essential for the synthesis of heparan sulfate, leading to abnormal physeal signaling and osteochondroma formation.

Question 94

Topic: Bone Tumors

An 18-year-old male presents with severe proximal focal tibial pain that worsens at night and is completely relieved by ibuprofen. Imaging reveals a cortically based radiolucent nidus surrounded by dense reactive sclerosis. The pain in this condition is primarily mediated by excessive production of which of the following?

. Interleukin-1
. Interleukin-6
. Prostaglandin E2
. Tumor Necrosis Factor-alpha
. Transforming Growth Factor-beta

Correct Answer & Explanation

. Prostaglandin E2

Explanation

Osteoid osteoma causes severe night pain due to a 100- to 1000-fold increase in local prostaglandin E2 (PGE2) production by the nidus cells. This explains the dramatic clinical response to cyclooxygenase inhibitors like NSAIDs.

Question 95

Topic: Bone Tumors
An 8-year-old girl is evaluated for precocious puberty, café-au-lait macules with irregular "coast of Maine" borders, and a "shepherd's crook" deformity of the proximal femur. This syndrome is caused by a somatic activating mutation in which of the following genes?
. FGFR3
. EXT1
. GNAS
. COMP
. COL1A1

Correct Answer & Explanation

. GNAS

Explanation

McCune-Albright syndrome consists of polyostotic fibrous dysplasia, café-au-lait spots, and endocrinopathies. It is caused by a somatic, post-zygotic activating mutation in the GNAS gene, leading to overproduction of intracellular cAMP.

Question 96

Topic: Bone Tumors

A patient with multiple bony protuberances around the knees and shoulders is diagnosed with Multiple Hereditary Exostoses (MHE). Genetic testing confirms a mutation in the EXT1 gene. This mutation directly impairs the synthesis of which of the following cell surface molecules?

. Heparan sulfate
. Chondroitin sulfate
. Hyaluronic acid
. Keratan sulfate
. Dermatan sulfate

Correct Answer & Explanation

. Heparan sulfate

Explanation

The EXT1 and EXT2 genes encode glycosyltransferases essential for the biosynthesis of heparan sulfate. Defective heparan sulfate synthesis alters chondrocyte signaling (such as Indian Hedgehog and PTHrP pathways), leading to the formation of osteochondromas.

Question 97

Topic: Bone Tumors

Which of the following clinical or radiographic features most reliably differentiates an osteoblastoma from an osteoid osteoma?

. Presence of a radiolucent nidus
. Dramatic response to nonsteroidal anti-inflammatory drugs (NSAIDs)
. Size greater than 2 cm in diameter with progressive pain
. Predilection for the diaphyseal cortex of long bones
. Production of abundant woven bone on histology

Correct Answer & Explanation

. Size greater than 2 cm in diameter with progressive pain

Explanation

Osteoblastomas are typically larger than 2 cm and lack the dramatic pain relief with NSAIDs seen in osteoid osteomas. Osteoid osteomas classically present with night pain relieved by NSAIDs and a nidus less than 1.5 to 2 cm.

Question 98

Topic: Bone Tumors

A 15-year-old girl is found to have multiple enchondromas localized primarily to one side of her body, alongside multiple soft tissue hemangiomas. Which of the following complications is she at the highest risk for compared to a patient with multiple enchondromas alone?

. Pathologic fracture of the femur
. Development of visceral malignancies
. Premature physeal closure
. Development of secondary chondrosarcoma
. Transformation to osteosarcoma

Correct Answer & Explanation

. Development of visceral malignancies

Explanation

The presentation describes Maffucci syndrome, distinguished from Ollier disease by the presence of soft tissue hemangiomas. Patients with Maffucci syndrome have a significantly higher risk of developing concurrent visceral malignancies (e.g., astrocytoma, GI tract) in addition to their chondrosarcoma risk.

Question 99

Topic: Bone Tumors

Which of the following factors has proven to increase the risk of degenerative disease of the wrist in patients with multiple hereditary osteochondromas:

. Ulnar negative variance of 5 mm
. Ulnar negative variance of 10 mm
. Distal radial articular slope larger than 25°
. Subluxation of the radial head
. None of the above

Correct Answer & Explanation

. None of the above

Explanation

The above findings are all more common in the forearms and wrists of patients with multiple hereditary exostoses than in the general population. However, there is no parameter shown to increase the risk of degenerative wrist disease.

Question 100

Topic: Bone Tumors

Which of the following bone lesions is shown to improve radiographically and clinically by use of systemic medication:

. Aneurysmal bone cyst
. Unicameral bone cyst
. Multiple exostoses
. Fibrous dysplasia
. Fibrous cortical defect

Correct Answer & Explanation

. Fibrous dysplasia

Explanation

In patients with polyostotic fibrous dysplasia, there is a decrease in pain and fracture rate and an improvement in radiodensity through the use of bisphosphonates. None of the other lesions mentioned respond radiographically to systemic medication.

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