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Bone Tumors MCQs

Practice Set 25 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 481

Topic: Bone Tumors
A 9-year-old girl presents with a progressive shepherd's crook deformity of the proximal femur, precocious puberty, and irregular hyperpigmented skin macules with 'coast of Maine' borders. Which of the following is the underlying genetic mutation responsible for this condition?
. GNAS1
. EXT1
. FGFR3
. COMP
. COL1A1

Correct Answer & Explanation

. GNAS1

Explanation

This patient presents with the classic triad of McCune-Albright syndrome: polyostotic fibrous dysplasia (shepherd's crook deformity), endocrine abnormalities (precocious puberty), and café-au-lait spots with irregular borders ('coast of Maine'). Fibrous dysplasia is a condition of anarchic development of bone constituents caused by a somatic activating mutation in the GNAS1 gene, which encodes the alpha subunit of the stimulatory G protein (Gs-alpha). This leads to increased intracellular cAMP, resulting in the proliferation of undifferentiated mesenchymal cells that replace normal marrow with fibrous tissue. EXT1 is associated with multiple hereditary exostoses, FGFR3 with achondroplasia, COMP with pseudoachondroplasia, and COL1A1 with osteogenesis imperfecta.

Question 482

Topic: Bone Tumors

When planning surgical correction for a severe shepherd's crook deformity in a patient with polyostotic fibrous dysplasia, which of the following fixation constructs is most appropriate to minimize the risk of recurrence and implant failure?

. Cortical bone grafting alone
. Load-bearing plate and screw construct
. Intramedullary nailing
. External fixation
. Cancellous bone grafting with K-wires

Correct Answer & Explanation

. Intramedullary nailing

Explanation

Correct Answer: Intramedullary nailingIn fibrous dysplasia, the bone is structurally weak due to the replacement of normal bone with woven bone and fibrous tissue. Surgical management of deformities, such as the shepherd's crook deformity of the proximal femur, requires osteotomies for realignment followed by robust fixation. Intramedullary nailing (a load-sharing device) is the gold standard because it protects the entire length of the bone and bypasses the dysplastic bone, significantly reducing the risk of implant failure and recurrent deformity. Load-bearing devices like plates and screws frequently fail because the screws pull out of the soft dysplastic bone. Bone grafting alone (especially cancellous) is ineffective as the graft is rapidly resorbed and replaced by dysplastic host tissue.

Question 483

Topic: Bone Tumors

A 10-year-old child with multiple hereditary exostoses presents with a progressive forearm deformity. Radiographs reveal a large sessile osteochondroma of the distal ulna. According to the Masada classification, which of the following is the most common associated deformity pattern in the forearm?

. Radial shortening with ulnar bowing and radial deviation of the carpus
. Ulnar shortening with radial bowing and ulnar deviation of the carpus
. Proximal radioulnar synostosis
. Dorsal subluxation of the distal radioulnar joint without bowing
. Volar dislocation of the radial head

Correct Answer & Explanation

. Ulnar shortening with radial bowing and ulnar deviation of the carpus

Explanation

Correct Answer: Ulnar shortening with radial bowing and ulnar deviation of the carpusIn multiple hereditary exostoses, forearm deformities are common and typically result from osteochondromas affecting the distal ulna (Masada Type I). Because the distal ulna contributes heavily to the longitudinal growth of the ulna, an osteochondroma here retards ulnar growth, leading to ulnar shortening. The radius continues to grow but is tethered to the shortened ulna, resulting in radial bowing. The loss of ulnar support at the wrist leads to an increased distal radial articular angle and subsequent ulnar deviation (ulnar slip) of the carpus. Radial head dislocation can occur in severe cases but is a secondary consequence of the primary ulnar shortening and radial bowing.

Question 484

Topic: Bone Tumors

A 4-year-old boy presents with an asymmetric, painless swelling of the medial aspect of his right ankle and a developing varus deformity. Radiographs show an irregular, stippled ossification mass arising from the medial epiphysis of the distal tibia. What is the most likely diagnosis?

. Multiple epiphyseal dysplasia
. Chondrodysplasia punctata
. Dysplasia epiphysealis hemimelica (Trevor disease)
. Spondyloepiphyseal dysplasia
. Ollier disease

Correct Answer & Explanation

. Dysplasia epiphysealis hemimelica (Trevor disease)

Explanation

Correct Answer: Dysplasia epiphysealis hemimelica (Trevor disease)Dysplasia epiphysealis hemimelica, also known as Trevor disease, is a rare developmental disorder characterized by an anarchic, asymmetric cartilaginous overgrowth of an epiphysis, most commonly affecting the lower extremity (ankle or knee). It behaves histologically like an osteochondroma but arises from the epiphysis rather than the metaphysis. It typically affects only one half of the epiphysis (hemimelica), leading to asymmetric growth, joint deformity (such as varus or valgus), and mechanical symptoms. Multiple epiphyseal dysplasia is bilateral and symmetric. Chondrodysplasia punctata presents with stippled epiphyses systemically in infancy. Ollier disease involves metaphyseal/diaphyseal enchondromas.

Question 485

Topic: Bone Tumors

A 14-year-old boy with polyostotic fibrous dysplasia presents with a progressive proximal femoral deformity characterized by severe varus angulation (Shepherd's crook deformity) and increasing hip pain. What is the most appropriate surgical management for this specific deformity?

. Curettage and autologous bone grafting
. Curettage and polymethylmethacrylate (PMMA) packing
. Valgus-producing proximal femoral osteotomy stabilized with an intramedullary device
. Valgus-producing proximal femoral osteotomy stabilized with a lateral plate and screws
. Observation and intravenous bisphosphonate therapy

Correct Answer & Explanation

. Valgus-producing proximal femoral osteotomy stabilized with an intramedullary device

Explanation

Correct Answer: Valgus-producing proximal femoral osteotomy stabilized with an intramedullary deviceIn fibrous dysplasia, the bone is replaced by structurally weak fibro-osseous tissue. Autologous bone graft is contraindicated as it will be resorbed and replaced by dysplastic bone. When correcting a Shepherd's crook deformity, intramedullary devices are strongly preferred over plates and screws. Plates have a high failure rate because screws cannot achieve adequate purchase in the dysplastic bone, leading to pull-out and loss of fixation. Intramedullary nails load-share and span the entire length of the lesion, providing superior biomechanical stability.

Question 486

Topic: Bone Tumors
An asymptomatic 25-year-old female undergoes a pelvic radiograph following a minor fall. The radiograph incidentally shows numerous small, symmetric, well-defined circular sclerotic foci clustered around the periarticular regions of the pelvis and proximal femurs. If this patient has an associated dermatological condition, what is the most likely diagnosis?
. McCune-Albright syndrome
. Maffucci syndrome
. Buschke-Ollendorff syndrome
. Mazabraud syndrome
. Neurofibromatosis type 1

Correct Answer & Explanation

. Buschke-Ollendorff syndrome

Explanation

The radiographic findings describe osteopoikilosis ('spotted bone disease'), an asymptomatic osteosclerotic dysplasia. When osteopoikilosis is associated with disseminated connective tissue nevi (elastomas or collagenomas) of the skin, it is termed Buschke-Ollendorff syndrome. Both isolated osteopoikilosis and Buschke-Ollendorff syndrome are inherited in an autosomal dominant pattern and are linked to mutations in the LEMD3 gene. Mazabraud syndrome is fibrous dysplasia with intramuscular myxomas. McCune-Albright is polyostotic fibrous dysplasia with café-au-lait spots and endocrine abnormalities.

Question 487

Topic: Bone Tumors

A 10-year-old boy with multiple hereditary exostoses (MHE) presents with a progressive forearm deformity. Which of the following is the most characteristic pattern of forearm deformity seen in this condition?

. Relative overgrowth of the ulna with radial deviation of the wrist
. Relative shortening of the ulna with bowing of the radius and ulnar deviation of the wrist
. Proximal radioulnar synostosis with fixed pronation
. Volar subluxation of the distal radioulnar joint with dorsal bowing of the radius
. Symmetrical shortening of both the radius and ulna without angular deformity

Correct Answer & Explanation

. Relative shortening of the ulna with bowing of the radius and ulnar deviation of the wrist

Explanation

Correct Answer: Relative shortening of the ulna with bowing of the radius and ulnar deviation of the wristIn Multiple Hereditary Exostoses (MHE), osteochondromas frequently affect the distal forearm. Because the distal ulna contributes a larger percentage to the overall longitudinal growth of the ulna compared to the radius, exostoses here disproportionately tether and stunt ulnar growth. This leads to relative ulnar shortening, secondary bowing of the radius (which continues to grow but is tethered to the short ulna), ulnar deviation of the carpus, and potential dislocation of the radial head (Madelung-like deformity).

Question 488

Topic: Bone Tumors
A 45-year-old female with a history of polyostotic fibrous dysplasia presents with a painless, slow-growing soft tissue mass in her right thigh. Magnetic resonance imaging (MRI) reveals a well-circumscribed, intramuscular lesion with high signal intensity on T2-weighted images and low signal on T1-weighted images. Biopsy confirms an intramuscular myxoma. What is the eponymous name for this specific association?
. McCune-Albright syndrome
. Jaffe-Campanacci syndrome
. Mazabraud syndrome
. Buschke-Ollendorff syndrome
. Klippel-Trenaunay syndrome

Correct Answer & Explanation

. Mazabraud syndrome

Explanation

Mazabraud syndrome is a rare disorder characterized by the association of fibrous dysplasia (usually polyostotic) and one or more intramuscular myxomas. The myxomas typically occur in the same anatomic region as the most severely affected bones. Jaffe-Campanacci syndrome is the association of multiple non-ossifying fibromas with café-au-lait spots. McCune-Albright syndrome involves fibrous dysplasia, café-au-lait spots, and precocious puberty/endocrine hyperfunction.

Question 489

Topic: Bone Tumors
A 12-year-old girl presents with a 'shepherd's crook' deformity of the proximal femur, café-au-lait spots with irregular 'coast of Maine' borders, and a history of precocious puberty. Which of the following best describes the underlying cellular pathophysiology of her skeletal lesions?
. Defective osteoclastic bone resorption due to a TCIRG1 mutation.
. Constitutive activation of adenylate cyclase leading to elevated intracellular cAMP.
. Mutation in the EXT1 gene leading to defective heparan sulfate synthesis.
. Defective type I collagen synthesis due to a COL1A1 mutation.
. Gain-of-function mutation in FGFR3 inhibiting chondrocyte proliferation.

Correct Answer & Explanation

. Constitutive activation of adenylate cyclase leading to elevated intracellular cAMP.

Explanation

This patient presents with the classic triad of McCune-Albright syndrome: polyostotic fibrous dysplasia, café-au-lait spots with irregular borders, and endocrine abnormalities (most commonly precocious puberty). The underlying cause is a post-zygotic somatic activating mutation in the GNAS1 gene. This mutation leads to constitutive activation of the Gs-alpha protein, which in turn causes continuous activation of adenylate cyclase and elevated levels of intracellular cyclic AMP (cAMP). This disrupts normal osteoblast differentiation, leading to the formation of immature woven bone and fibrous tissue characteristic of fibrous dysplasia.

Question 490

Topic: Bone Tumors

A 22-year-old female with polyostotic fibrous dysplasia presents with progressive hip pain and a severe 'shepherd's crook' deformity of the proximal femur. She has an impending subtrochanteric fracture. Which of the following surgical constructs is most appropriate for stabilizing this lesion after corrective osteotomy?

. Cancellous bone grafting and dynamic hip screw (DHS) fixation.
. Cortical strut allografting and isolated screw fixation.
. External fixation to allow gradual deformity correction.
. Curettage, polymethylmethacrylate (PMMA) packing, and a laterally based plate.
. Valgus producing osteotomy stabilized with an intramedullary nail.

Correct Answer & Explanation

. Valgus producing osteotomy stabilized with an intramedullary nail.

Explanation

Correct Answer: Valgus producing osteotomy stabilized with an intramedullary nail.In fibrous dysplasia, the bone is structurally weak and prone to progressive deformity and fracture. The 'shepherd's crook' deformity requires a valgus-producing osteotomy to restore mechanical alignment. Fixation must span the entire length of the diseased bone to prevent stress risers and subsequent fractures. Intramedullary nailing is the gold standard because it provides load-sharing biomechanics along the entire diaphysis. Plates and screws (load-bearing) have a high failure rate due to poor screw purchase in dysplastic bone. Bone grafting (especially cancellous) is generally ineffective as the graft is rapidly resorbed and replaced by dysplastic fibrous tissue.

Question 491

Topic: Bone Tumors
A 6-year-old girl presents with a limp and a leg-length discrepancy. Radiographs reveal a 'shepherd's crook' deformity of the proximal femur with a ground-glass appearance in the medullary canal. Physical examination notes large, irregular hyperpigmented macules with jagged borders ('Coast of Maine'). Which of the following endocrine abnormalities is most commonly associated with this patient's syndrome?
. Hypothyroidism
. Precocious puberty
. Hyperparathyroidism
. Diabetes insipidus
. Adrenal insufficiency

Correct Answer & Explanation

. Precocious puberty

Explanation

The patient's presentation of polyostotic fibrous dysplasia (shepherd's crook deformity, ground-glass bone lesions) and café-au-lait spots with irregular borders ('Coast of Maine') is diagnostic of McCune-Albright syndrome. This syndrome is caused by a post-zygotic somatic activating mutation in the GNAS gene, leading to overproduction of cAMP. The most common endocrine manifestation of McCune-Albright syndrome is peripheral precocious puberty, particularly in females, due to autonomous ovarian estrogen production.

Question 492

Topic: Bone Tumors

A 15-year-old male undergoes intralesional curettage of a pathologically confirmed chondroblastoma of the proximal tibial epiphysis.

During the procedure, a secondary cystic, hemorrhagic, and multiloculated cavity is encountered adjacent to the primary tumor. What is the most likely diagnosis of this secondary lesion?

. Unicameral bone cyst
. Osteosarcoma
. Aneurysmal bone cyst
. Giant cell tumor of bone
. Enchondroma

Correct Answer & Explanation

. Aneurysmal bone cyst

Explanation

Secondary aneurysmal bone cysts (ABCs) occur in up to 15-20% of chondroblastomas. They present as blood-filled, multiloculated cavities that often require concurrent aggressive curettage to prevent recurrence.

Question 493

Topic: Bone Tumors

Histological evaluation of a curettage specimen from a proximal humerus lesion reveals sheets of mononuclear cells with "coffee-bean" nuclei, interspersed osteoclast-like giant cells, and delicate pericellular calcifications.

This constellation of findings is diagnostic for:

. Chondroblastoma
. Giant cell tumor of bone
. Clear cell chondrosarcoma
. Chondromyxoid fibroma
. Aneurysmal bone cyst

Correct Answer & Explanation

. Chondroblastoma

Explanation

The histological triad of mononuclear cells with clefted ("coffee-bean") nuclei, scattered osteoclast-like giant cells, and "chicken-wire" (pericellular) calcifications is pathognomonic for chondroblastoma.

Question 494

Topic: Bone Tumors

A 40-year-old female with diffuse systemic sclerosis presents with palpable grating over the flexor tendons of her wrists and ankles during active motion. The presence of these tendon friction rubs is most strongly associated with an increased risk for which of the following?

. Progression to limited cutaneous sclerosis
. Development of osteosarcoma
. Severe internal organ involvement and reduced survival
. Avascular necrosis of the femoral head
. Acute septic arthritis

Correct Answer & Explanation

. Severe internal organ involvement and reduced survival

Explanation

Tendon friction rubs are highly specific to the diffuse cutaneous form of systemic sclerosis. Their presence is a poor prognostic marker, strongly associated with severe skin thickening, restrictive lung disease, renal crisis, and reduced overall survival.

Question 495

Topic: Bone Tumors
A 22-year-old female presents with multiple enchondromas localized primarily to the left side of her body, including the hand and femur. There are no associated soft tissue hemangiomas. What is the most likely diagnosis?
. Maffucci Syndrome
. McCune-Albright Syndrome
. Ollier's Disease
. Trevor's Disease
. Jaffé-Campanacci Syndrome

Correct Answer & Explanation

. Ollier's Disease

Explanation

Ollier's disease (enchondromatosis) is characterized by multiple enchondromas, often with a unilateral or asymmetrical distribution. Unlike Maffucci syndrome, it does not involve soft tissue hemangiomas. It is a non-hereditary condition resulting from somatic mutations.

Question 496

Topic: Bone Tumors

Which of the following conditions carries the highest lifetime risk (approaching 100% in some series) for the development of both skeletal and extra-skeletal malignancies, including visceral carcinomas?

. Monostotic Fibrous Dysplasia
. Ollier's Disease
. Maffucci Syndrome
. Hereditary Multiple Exostoses
. Dysplasia Epiphysealis Hemimelica

Correct Answer & Explanation

. Maffucci Syndrome

Explanation

Correct Answer: CMaffucci syndrome (Enchondromatosis plus hemangiomas) carries a significantly higher risk of malignancy than Ollier's disease. Patients have a very high risk of chondrosarcoma and are also predisposed to visceral malignancies such as gliomas and ovarian carcinomas.

Question 497

Topic: Bone Tumors
A 9-year-old girl presents with a 'Shepherd's crook' deformity of the proximal femur and large, irregular café-au-lait spots with 'Coast of Maine' borders. Which molecular defect is responsible for this condition?
. Mutation in the COL1A1 gene
. Constitutive activation of the GNAS gene
. Inactivation of the EXT2 gene
. Deficiency of Alkaline Phosphatase
. Mutation in the FGFR3 gene

Correct Answer & Explanation

. Constitutive activation of the GNAS gene

Explanation

The patient has McCune-Albright syndrome (polyostotic fibrous dysplasia, café-au-lait spots, and precocious puberty). This is caused by a post-zygotic somatic mutation in the GNAS gene, leading to constitutive activation of the alpha subunit of the stimulatory G-protein (Gs-alpha) and increased intracellular cAMP.

Question 498

Topic: Bone Tumors

Radiographic evaluation of a 15-year-old's femur shows a well-circumscribed intramedullary lesion with a 'ground-glass' appearance and a thin sclerotic rim (rind sign). What is the most appropriate initial management for an asymptomatic monostotic lesion in this location?

. Immediate wide resection and endoprosthetic replacement
. Curettage and autologous bone grafting
. Observation with serial radiographs
. High-dose radiation therapy
. Systemic chemotherapy

Correct Answer & Explanation

. Observation with serial radiographs

Explanation

Correct Answer: CAsymptomatic monostotic Fibrous Dysplasia (FD) often does not require surgical intervention and can be managed with observation. Surgery (curettage, grafting, or stabilization) is reserved for lesions that are symptomatic, causing significant deformity, or at high risk of pathological fracture.

Question 499

Topic: Bone Tumors

In the surgical management of a 'Shepherd's crook' deformity in a patient with Fibrous Dysplasia, which of the following is the preferred method of fixation to prevent recurrence of the deformity?

. Isolated Cortical Bone Grafting
. Compression Hip Screw (CHS)
. Intramedullary Nailing (e.g., Cephalomedullary nail)
. External Fixation
. Plate and Screw fixation only

Correct Answer & Explanation

. Intramedullary Nailing (e.g., Cephalomedullary nail)

Explanation

Correct Answer: CFor the Shepherd's crook deformity in Fibrous Dysplasia, intramedullary fixation is preferred over plates or bone grafts alone. Intramedullary devices provide better load-sharing and support the entire weakened femoral shaft, reducing the high rate of deformity recurrence seen with other methods.

Question 500

Topic: Bone Tumors

Maffucci syndrome is distinguished from Ollier disease by the presence of which of the following clinical features?

. Autosomal dominant inheritance pattern
. Soft tissue hemangiomas
. Precocious puberty
. Polyostotic fibrous dysplasia
. Blue sclera and dentinogenesis imperfecta

Correct Answer & Explanation

. Soft tissue hemangiomas

Explanation

Correct Answer: BMaffucci syndrome is characterized by multiple enchondromas (similar to Ollier disease) plus soft tissue hemangiomas (often spindle-cell hemangiomas). Both conditions are non-hereditary and result from somatic mutations (IDH1 or IDH2).

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