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Bone Tumors MCQs

Practice Set 51 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 1001

Topic: Bone Tumors

A 5-year-old boy presents with a painless, asymmetric, hard swelling on the medial aspect of his right ankle. Radiographs demonstrate an irregular, stippled ossification mass arising directly from the medial epiphysis of the distal tibia. If this lesion were to be excised and examined histologically, the tissue would most closely resemble which of the following?

. Osteochondroma
. Chondroblastoma
. Enchondroma
. Osteoid osteoma
. Chondromyxoid fibroma

Correct Answer & Explanation

. Osteochondroma

Explanation

Correct Answer: A (Osteochondroma)The clinical and radiographic presentation is classic for Dysplasia Epiphysealis Hemimelica (also known as Trevor disease). This is a rare developmental disorder characterized by asymmetric cartilage overgrowth in the epiphyses, most commonly affecting the medial side of the lower extremity (ankle or knee). Histologically, the lesion is indistinguishable from an osteochondroma, consisting of a cartilage cap with underlying endochondral ossification. It is essentially an intra-articular osteochondroma arising from the epiphysis.

Question 1002

Topic: Bone Tumors

A 19-year-old male presents with worsening right thigh pain that is particularly severe at night and dramatically improves with ibuprofen. Radiographs show a small radiolucent nidus surrounded by dense sclerotic bone in the proximal femoral diaphysis. What is the primary biochemical mediator responsible for this patient's pain pattern?

. Interleukin-1
. Tumor necrosis factor-alpha
. Prostaglandin E2
. Leukotriene B4
. Transforming growth factor-beta

Correct Answer & Explanation

. Prostaglandin E2

Explanation

Osteoid osteomas characteristically cause nocturnal pain that is relieved by NSAIDs. This is due to the high levels of Prostaglandin E2 produced by the nidus, which NSAIDs effectively inhibit.

Question 1003

Topic: Bone Tumors

A patient presents with sparse hair, a pear-shaped nose, and cone-shaped epiphyses of the hands. Additionally, the patient has multiple osteochondromas throughout the appendicular skeleton. Which contiguous gene deletion syndrome is this?

. TRPS Type 1
. TRPS Type 2 (Langer-Giedion syndrome)
. TRPS Type 3
. Trevor disease
. Ollier disease

Correct Answer & Explanation

. TRPS Type 2 (Langer-Giedion syndrome)

Explanation

TRPS Type 2 (Langer-Giedion syndrome) is a contiguous gene deletion syndrome affecting both TRPS1 (causing TRPS features) and EXT1 (causing multiple hereditary exostoses).

Question 1004

Topic: Bone Tumors
A rare subtype of autosomal recessive osteopetrosis is caused by a deficiency in carbonic anhydrase II (CA II). This specific genetic mutation is characteristically associated with which of the following triads?
. Osteopetrosis, renal tubular acidosis, and cerebral calcification
. Osteopetrosis, sensorineural deafness, and blue sclerae
. Osteopetrosis, multiple osteochondromas, and mental retardation
. Osteopetrosis, primary hyperparathyroidism, and pituitary adenoma
. Osteopetrosis, precocious puberty, and café-au-lait spots

Correct Answer & Explanation

. Osteopetrosis, renal tubular acidosis, and cerebral calcification

Explanation

Carbonic anhydrase II (CA II) deficiency causes a unique syndrome characterized by the triad of osteopetrosis, renal tubular acidosis, and cerebral calcifications (Guibaud-Vainsel syndrome).

Question 1005

Topic: Bone Tumors

Trichorhinophalangeal Syndrome (TRPS) Type 2, also known as Langer-Giedion syndrome, is a contiguous gene deletion syndrome involving chromosome 8q23.3-q24.1. Which of the following phenotypic features reliably differentiates TRPS Type 2 from TRPS Type 1?

. Intellectual disability and multiple osteochondromas
. Deafness and blue sclerae
. Craniosynostosis and severe syndactyly
. Osteomyelitis of the jaw and cranial nerve palsies
. Hypercalcemia and recurrent renal stones

Correct Answer & Explanation

. Intellectual disability and multiple osteochondromas

Explanation

TRPS Type 2 is caused by the deletion of both the TRPS1 gene (causing TRPS features) and the adjacent EXT1 gene (causing multiple osteochondromas). It is also frequently accompanied by intellectual disability, unlike TRPS Type 1.

Question 1006

Topic: Bone Tumors

A 12-year-old girl is evaluated for short stature and joint deformities. Hand radiographs are obtained.

The image shows classic cone-shaped epiphyses. Which of the following physical examination findings is most consistently associated with this syndrome?

. Blue sclerae and dentinogenesis imperfecta
. Pear-shaped bulbous nose and sparse, thin hair
. Multiple cafe-au-lait spots and axillary freckling
. Precocious puberty and polyostotic fibrous dysplasia
. Enamel hypoplasia and delayed tooth eruption

Correct Answer & Explanation

. Pear-shaped bulbous nose and sparse, thin hair

Explanation

Cone-shaped epiphyses in the phalanges are a hallmark of Trichorhinophalangeal Syndrome (TRPS) Type 1. Clinically, patients present with a distinct facial phenotype including a bulbous (pear-shaped) nose, elongated philtrum, and sparse, fine hair.

Question 1007

Topic: Bone Tumors

A 14-year-old girl presents with a 'Shepherd's crook' deformity of the proximal femur and a 'ground-glass' appearance on radiographs. Genetic testing reveals a somatic mutation in the GNAS gene. Which of the following is the most likely diagnosis?

. Osteogenesis Imperfecta
. Fibrous Dysplasia
. Osteopetrosis
. Multiple Hereditary Exostoses
. Paget's Disease

Correct Answer & Explanation

. Fibrous Dysplasia

Explanation

Correct Answer: BFibrous dysplasia is caused by a somatic mutation in the GNAS gene, leading to the replacement of normal bone with fibrous tissue and immature trabecular bone (ground-glass appearance). The 'Shepherd's crook' deformity is a classic varus deformity of the proximal femur seen in polyostotic fibrous dysplasia.

Question 1008

Topic: Bone Tumors

A 10-year-old girl presents with precocious puberty, large 'cafe-au-lait' spots with irregular 'coast of Maine' borders, and polyostotic fibrous dysplasia. What is the underlying pathophysiology?

. Deficiency of Type 1 Collagen
. Constitutively active Gs-alpha protein signaling
. Inactivation of the EXT2 tumor suppressor gene
. Overexpression of Fibroblast Growth Factor 23 (FGF23)
. Mutation in the Cathepsin K gene

Correct Answer & Explanation

. Constitutively active Gs-alpha protein signaling

Explanation

Correct Answer: BThe triad of polyostotic fibrous dysplasia, cafe-au-lait spots, and hyperfunctioning endocrinopathies (like precocious puberty) defines McCune-Albright Syndrome. It is caused by a post-zygotic somatic mutation in the GNAS1 gene, which leads to constitutive activation of the Gs-alpha protein, stimulating adenylate cyclase and increasing intracellular cAMP.

Question 1009

Topic: Bone Tumors

A 5-year-old boy presents with a hard, painless swelling on the medial aspect of his right ankle and a progressive varus deformity. Radiographs show an irregular, multicentric radiopaque mass arising as an asymmetric overgrowth from the medial epiphysis of the distal tibia. What is the most likely diagnosis?

. Multiple hereditary exostoses
. Dysplasia epiphysealis hemimelica
. Chondroblastoma
. Ollier disease
. Osteopathia striata

Correct Answer & Explanation

. Dysplasia epiphysealis hemimelica

Explanation

Dysplasia epiphysealis hemimelica (Trevor disease) is a rare developmental disorder characterized by an osteochondroma-like asymmetric overgrowth of the epiphysis. It most commonly affects the medial side of the ankle or knee in young boys.

Question 1010

Topic: Bone Tumors

A 4-year-old boy presents with painless, localized swelling on the medial aspect of his ankle. Radiographs reveal an asymmetric, irregular ossification mass arising from the medial half of the distal tibial epiphysis. What is the most likely diagnosis?

. Chondroblastoma
. Dysplasia epiphysealis hemimelica
. Osteochondroma
. Osteopathia striata
. Melorheostosis

Correct Answer & Explanation

. Dysplasia epiphysealis hemimelica

Explanation

Dysplasia epiphysealis hemimelica (Trevor disease) is an osteochondroma-like overgrowth of an epiphysis. It is typically unilateral, primarily involves the medial half of the lower extremity joints, and causes localized deformity.

Question 1011

Topic: Bone Tumors
A 15-year-old female presents with an aching pain in her right thigh. Radiographs demonstrate a radiolucent, ground-glass expansile lesion in the proximal femur resulting in a shepherd's crook deformity. If café-au-lait spots with irregular borders are also present, which endocrine abnormality must be screened for?
. Hyperparathyroidism
. Precocious puberty
. Hypothyroidism
. Diabetes insipidus
. Adrenal insufficiency

Correct Answer & Explanation

. Precocious puberty

Explanation

Monostotic or polyostotic fibrous dysplasia combined with café-au-lait spots and endocrine dysfunction defines McCune-Albright syndrome. The most common endocrine manifestation is precocious puberty, driven by an activating somatic mutation in GNAS.

Question 1012

Topic: Bone Tumors

A 5-year-old boy presents with an asymmetric, painless swelling on the medial side of his ankle. Imaging shows an asymmetric cartilaginous overgrowth originating from the medial distal tibial epiphysis. Which of the following best describes the typical histological appearance of this lesion?

. Resembles a classic osteochondroma
. Shows highly atypical chondrocytes
. Consists of woven bone without cartilage
. Fibrocartilaginous cap with cellular stroma
. Organized mature lamellar bone without a cartilaginous cap

Correct Answer & Explanation

. Resembles a classic osteochondroma

Explanation

Trevor disease (dysplasia epiphysealis hemimelica) is characterized by an osteochondroma-like overgrowth of a portion of the epiphysis, typically on the medial side of the lower extremity. Histologically, it is virtually indistinguishable from a classic osteochondroma.

Question 1013

Topic: Bone Tumors

A 14-year-old boy presents with a painless limp. Pelvic radiographs display a well-defined, radiolucent lesion with a ground-glass appearance in the proximal femur, causing a shepherd's crook varus deformity. A somatic activating mutation in which of the following genes is responsible for this lesion?

. EXT1
. GNAS
. COMP
. FGFR3
. SOX9

Correct Answer & Explanation

. GNAS

Explanation

Fibrous dysplasia is caused by a sporadic, somatic activating mutation in the GNAS gene. This leads to increased intracellular cAMP, causing abnormal proliferation and differentiation of osteoblasts.

Question 1014

Topic: Bone Tumors

A 5-year-old boy presents with a painless, progressively enlarging swelling on the medial aspect of his right ankle. Radiographs demonstrate an asymmetric, irregular mass of ossifying cartilage arising from the medial epiphysis of the distal tibia. What is the most likely diagnosis?

. Multiple epiphyseal dysplasia
. Dysplasia epiphysealis hemimelica (Trevor disease)
. Chondroblastoma
. Enchondromatosis (Ollier disease)
. Osteochondroma

Correct Answer & Explanation

. Dysplasia epiphysealis hemimelica (Trevor disease)

Explanation

Dysplasia epiphysealis hemimelica (Trevor disease) is a rare developmental disorder characterized by an asymmetrical, osteochondroma-like overgrowth of cartilage in an epiphysis, most commonly affecting the medial side of the ankle or knee.

Question 1015

Topic: Bone Tumors

A 4-year-old boy presents with an asymmetric, painless swelling on the medial aspect of his left ankle. Radiographs reveal irregular ossification centers arising from the medial epiphysis of the distal tibia, resembling an intra-articular osteochondroma. What is the most likely diagnosis?

. Dysplasia epiphysealis hemimelica
. Multiple hereditary exostoses
. Fibrodysplasia ossificans progressiva
. Melorheostosis
. Chondrodysplasia punctata

Correct Answer & Explanation

. Dysplasia epiphysealis hemimelica

Explanation

Dysplasia epiphysealis hemimelica (Trevor disease) is a localized developmental abnormality characterized by asymmetric osteochondral overgrowth of an epiphysis. It most commonly affects the medial side of the lower extremity joints, particularly the ankle or knee.

Question 1016

Topic: Bone Tumors

A 5-year-old boy presents with a painless, asymmetric swelling over the medial aspect of his right ankle. Radiographs demonstrate an irregular, multicentric ossification center arising from the medial epiphysis of the distal tibia. What is the most appropriate initial management for this condition?

. Immediate wide excision
. Observation if asymptomatic
. Below-knee amputation
. Administration of bisphosphonates
. Curettage and bone grafting

Correct Answer & Explanation

. Observation if asymptomatic

Explanation

Dysplasia epiphysealis hemimelica (Trevor disease) is a rare focal skeletal dysplasia presenting as asymmetrical epiphyseal overgrowth, pathologically identical to an osteochondroma. Asymptomatic lesions are observed, while surgery is reserved for pain, progressive deformity, or mechanical mechanical restriction.

Question 1017

Topic: Bone Tumors

A 50-year-old male presents with insidious thigh pain. Radiographs appear largely normal, but an MRI is obtained.

Which of the following MRI features is considered classic for primary bone lymphoma?

. Fluid-fluid levels on T2-weighted images
. A "dot-in-circle" sign on contrast-enhanced images
. Extensive marrow replacement and soft tissue mass out of proportion to cortical destruction
. The "penumbra sign" on T1-weighted images
. A distinct sclerotic rim surrounding a hyperintense nidus

Correct Answer & Explanation

. Extensive marrow replacement and soft tissue mass out of proportion to cortical destruction

Explanation

A hallmark of primary bone lymphoma is massive marrow involvement and soft tissue extension through cortical channels, producing minimal to no gross cortical bone destruction on plain radiographs.

Question 1018

Topic: Bone Tumors

A 20-year-old male presents with chronic pain below the knee. A radiograph is obtained.

Which radiographic description best characterizes this lesion, consistent with Chondromyxoid fibroma?

. A centrally located epiphyseal lesion with stippled calcifications
. An eccentric, sharply circumscribed metaphyseal lucency with a sclerotic rim
. A permeative diaphyseal lesion with Codman's triangle
. An expansile diaphyseal lesion giving a ground-glass appearance
. A cortical lucency with a surrounding dense sclerotic nidus

Correct Answer & Explanation

. An eccentric, sharply circumscribed metaphyseal lucency with a sclerotic rim

Explanation

CMF typically presents as an eccentric, geographic, osteolytic lesion in the metaphysis with a well-defined, scalloped sclerotic margin. Intralesional calcification is rarely visible on plain radiographs.

Question 1019

Topic: Bone Tumors

When distinguishing a chondromyxoid fibroma (CMF) from a chondroblastoma based on clinical and histologic criteria, which of the following features is most indicative of CMF?

. Predilection for the epiphysis of long bones prior to physeal closure
. Presence of 'chicken-wire' calcifications surrounding mononuclear cells
. Eccentric metaphyseal location with distinct lobular architecture
. Production of extensive and mature true hyaline cartilage
. Frequent association with secondary aneurysmal bone cysts

Correct Answer & Explanation

. Eccentric metaphyseal location with distinct lobular architecture

Explanation

CMF typically presents as an eccentric metaphyseal lesion with lobular architecture consisting of myxoid and chondroid zones. Chondroblastomas are classically epiphyseal and feature 'chicken-wire' calcifications.

Question 1020

Topic: Bone Tumors
A 7-year-old girl presents with a limp and a noticeable leg-length discrepancy. Radiographs reveal a 'shepherd's crook' deformity of the proximal femur with a characteristic ground-glass appearance in the medullary canal. Physical examination shows irregular, 'coast of Maine' café-au-lait spots on her torso. Which of the following endocrine abnormalities is most commonly associated with this patient's underlying condition?
. Precocious puberty
. Hypothyroidism
. Hyperparathyroidism
. Diabetes insipidus
. Adrenal insufficiency

Correct Answer & Explanation

. Precocious puberty

Explanation

This patient presents with the classic triad of McCune-Albright syndrome: polyostotic fibrous dysplasia (shepherd's crook deformity, ground-glass bone lesions), café-au-lait spots with irregular borders ('coast of Maine'), and endocrine hyperfunction. The most common endocrine abnormality in McCune-Albright syndrome is precocious puberty, particularly in females. It is caused by a post-zygotic somatic activating mutation in the GNAS1 gene, leading to overproduction of cAMP.

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