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Bone Tumors MCQs

Practice Set 43 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 841

Topic: Bone Tumors

A 12-year-old girl undergoes extended intralesional curettage, high-speed burring, and phenol adjuvant therapy for an aneurysmal bone cyst of the distal tibia. Despite adequate initial surgery, the lesion recurs 1 year later without soft tissue extension. What is the next most appropriate step in management?

. Below-knee amputation
. External beam radiation therapy
. Repeat extended curettage with adjuvant therapy and bone grafting
. Systemic neo-adjuvant chemotherapy
. Wide en bloc resection of the distal tibia

Correct Answer & Explanation

. Repeat extended curettage with adjuvant therapy and bone grafting

Explanation

Aneurysmal bone cysts have a recurrence rate of 10-20% even with modern curettage techniques. The standard treatment for a local, contained recurrence remains repeat extended intralesional curettage with local adjuvant therapy (e.g., phenol, cryotherapy, or argon beam) and grafting.

Question 842

Topic: Bone Tumors

A 12-year-old girl presents with precocious puberty, cafe-au-lait spots with irregular 'coast of Maine' borders, and a radiolucent 'ground glass' lesion in her proximal femur causing a shepherd's crook deformity. What is the underlying pathophysiology of her bone disease?

. Failure of osteoclast resorption leading to dense bone
. Activating mutation of Gs-alpha (GNAS1 gene) leading to increased cAMP
. Vitamin D deficiency causing unmineralized osteoid
. Abnormal production of type 1 collagen causing brittle bones
. Defect in the parathyroid hormone receptor

Correct Answer & Explanation

. Activating mutation of Gs-alpha (GNAS1 gene) leading to increased cAMP

Explanation

This presentation is classic for McCune-Albright syndrome, consisting of polyostotic fibrous dysplasia, cafe-au-lait macules, and endocrine abnormalities. It is caused by a somatic activating mutation in the GNAS1 gene, resulting in elevated intracellular cAMP.

Question 843

Topic: Bone Tumors

A 15-year-old boy presents with severe, dull aching pain in his proximal thigh that worsens at night and is dramatically relieved by ibuprofen. Imaging shows an 8mm intracortical radiolucent nidus with dense surrounding sclerosis. What is the standard of care for definitive, minimally invasive treatment?

. En bloc resection with wide margins
. Curettage and structural bone grafting
. CT-guided Radiofrequency Ablation (RFA)
. Percutaneous cryotherapy
. External beam radiation therapy

Correct Answer & Explanation

. CT-guided Radiofrequency Ablation (RFA)

Explanation

The clinical and radiographic presentation is classic for an Osteoid Osteoma. CT-guided Radiofrequency Ablation (RFA) is the treatment of choice, offering high success rates with minimal morbidity.

Question 844

Topic: Bone Tumors

The mnemonic 'CRAB' is used to recall the hallmark end-organ damage manifestations of Multiple Myeloma. Which of the following accurately represents the CRAB criteria?

. Hypercalcemia, Renal insufficiency, Anemia, Bone lesions
. Hypocalcemia, Renal hyperfiltration, Polycythemia, Bone lesions
. Hyperkalemia, Renal insufficiency, Anemia, Bone lesions
. Hypercalcemia, Hepatic failure, Leukopenia, Bone lesions
. Normal calcium, Normal renal function, Normal hemoglobin, Bone lesions

Correct Answer & Explanation

. Hypercalcemia, Renal insufficiency, Anemia, Bone lesions

Explanation

The CRAB criteria defining end-organ damage in symptomatic multiple myeloma stand for hyperCalcemia, Renal insufficiency, Anemia, and Bone lesions (lytic).

Question 845

Topic: Bone Tumors



A 65-year-old male presents with new-onset back pain, fatigue, and hypercalcemia. Radiographs show multiple punched-out lytic lesions in the axial skeleton, as seen in the provided image. Which laboratory finding is most specific for confirming the diagnosis of this pathology?

. Elevated alkaline phosphatase
. Monoclonal spike on serum protein electrophoresis
. Low serum parathyroid hormone levels
. Elevated prostate-specific antigen
. Elevated serum phosphorus

Correct Answer & Explanation

. Monoclonal spike on serum protein electrophoresis

Explanation

The clinical picture and lytic lesions represent multiple myeloma. A monoclonal spike (M-protein) on serum protein electrophoresis (SPEP) or urine protein electrophoresis (UPEP) is a hallmark finding, confirming the clonal plasma cell proliferation.

Question 846

Topic: Bone Tumors

A 16-year-old boy presents with a 6-month history of right thigh pain that is worse at night and completely relieved by ibuprofen. Radiographs show a 1 cm radiolucent nidus surrounded by dense sclerotic bone. The profound pain relief from NSAIDs is due to inhibition of which substance produced by the nidus?

. Interleukin-1
. Prostaglandin E2
. Tumor necrosis factor-alpha
. Substance P
. Bradykinin

Correct Answer & Explanation

. Prostaglandin E2

Explanation

Osteoid osteomas classically cause night pain relieved by NSAIDs. This occurs because the nidus produces extremely high levels of Prostaglandin E2 (PGE2), which is inhibited by cyclooxygenase (COX) inhibitors.

Question 847

Topic: Bone Tumors

A 68-year-old male presents with fatigue, diffuse bone pain, and hypercalcemia. A representative radiograph is shown.

Serum protein electrophoresis confirms a monoclonal gammopathy. When evaluating the extent of this patient's skeletal disease, which of the following imaging modalities is most likely to yield false-negative results due to the underlying pathophysiology of the bone lesions?

. Whole-body MRI
. Low-dose whole-body CT
. Technetium-99m bone scintigraphy
. F-18 FDG PET/CT
. Conventional skeletal survey

Correct Answer & Explanation

. Technetium-99m bone scintigraphy

Explanation

Technetium-99m bone scintigraphy relies on osteoblastic activity for radiotracer uptake. In multiple myeloma, neoplastic cells secrete factors (such as DKK-1) that profoundly suppress osteoblasts, leading to purely lytic lesions that frequently do not demonstrate uptake on traditional bone scans.

Question 848

Topic: Bone Tumors
A 9-year-old girl presents with a proximal femur fracture. Radiographs show a "ground-glass" appearance in the proximal femur. She is noted to have precocious puberty and café-au-lait spots with irregular borders. Which mutation is responsible for this condition?
. GNAS1
. EXT1
. NF1
. FGFR3
. COL1A1

Correct Answer & Explanation

. GNAS1

Explanation

McCune-Albright syndrome is a triad of polyostotic fibrous dysplasia, endocrinopathies (precocious puberty), and coast-of-Maine café-au-lait spots. It is caused by a somatic activating mutation in the GNAS1 gene.

Question 849

Topic: Bone Tumors
A 12-year-old girl presents with precocious puberty, irregular 'coast of Maine' café-au-lait spots, and a progressive proximal femur deformity. Radiographs reveal expansile, ground-glass lesions in the femur and pelvis. What is the underlying molecular pathogenesis of her skeletal condition?
. Mutation in the EXT1 gene leading to defective heparan sulfate synthesis
. Activating mutation of the GNAS1 gene leading to increased intracellular cAMP
. Mutation in the FGFR3 gene leading to abnormal endochondral ossification
. Defect in type I collagen synthesis leading to brittle bone matrix

Correct Answer & Explanation

. Activating mutation of the GNAS1 gene leading to increased intracellular cAMP

Explanation

This patient presents with McCune-Albright syndrome, characterized by the triad of polyostotic fibrous dysplasia, precocious puberty (or other endocrinopathies), and café-au-lait spots with irregular borders ('coast of Maine'). The underlying cause is a post-zygotic somatic activating mutation in the GNAS1 gene, which encodes the alpha subunit of the stimulatory G protein (Gs). This leads to constitutive activation of adenylate cyclase and elevated intracellular cyclic AMP (cAMP), resulting in abnormal proliferation and differentiation of preosteoblasts.

Question 850

Topic: Bone Tumors

An 18-year-old patient with polyostotic fibrous dysplasia presents with a progressive 'shepherd's crook' deformity of the proximal femur and a recent pathological fracture. Which of the following is the most appropriate surgical stabilization principle for this patient?

. Curettage and packing with autologous cancellous bone graft
. Open reduction and internal fixation with a dynamic hip screw and side plate
. Valgus osteotomy and stabilization with a load-sharing intramedullary device
. Wide resection and endoprosthetic reconstruction of the proximal femur

Correct Answer & Explanation

. Valgus osteotomy and stabilization with a load-sharing intramedullary device

Explanation

Correct Answer: Valgus osteotomy and stabilization with a load-sharing intramedullary deviceThe surgical management of fibrous dysplasia, particularly the 'shepherd's crook' deformity of the proximal femur, requires careful consideration of the abnormal bone biology. Cortical and cancellous bone grafts are typically resorbed and replaced by dysplastic bone, making simple curettage and grafting ineffective. Plate fixation is prone to failure due to the poor quality of the dysplastic bone and the massive bending forces. The gold standard is correction of the mechanical axis (valgus osteotomy) combined with a load-sharing intramedullary device (e.g., reconstruction nail) to protect the entire length of the affected bone.

Question 851

Topic: Bone Tumors

In the context of Multiple Hereditary Exostoses (MHE), which of the following cellular processes is primarily disrupted by the underlying genetic mutation?

. Fibroblast growth factor receptor signaling in the proliferative zone
. Synthesis of heparan sulfate proteoglycans in the Golgi apparatus
. Cyclic AMP production in preosteoblasts
. Formation of the osteoclast ruffled border

Correct Answer & Explanation

. Synthesis of heparan sulfate proteoglycans in the Golgi apparatus

Explanation

Correct Answer: Synthesis of heparan sulfate proteoglycans in the Golgi apparatusMultiple Hereditary Exostoses (MHE) is caused by autosomal dominant mutations in the EXT1 or EXT2 genes. These genes encode glycosyltransferases localized to the Golgi apparatus, which are essential for the polymerization and synthesis of heparan sulfate proteoglycans (HSPGs). Deficiency in HSPGs disrupts normal Indian hedgehog (Ihh) signaling and chondrocyte proliferation/differentiation at the growth plate, leading to the formation of osteochondromas.

Question 852

Topic: Bone Tumors

A 12-year-old girl presents with a progressive 'shepherd's crook' deformity of the proximal femur and large, irregularly bordered hyperpigmented skin macules. Which of the following best describes the underlying molecular pathogenesis of her skeletal condition?

. Mutation in the EXT1 gene leading to heparan sulfate deficiency
. Gain-of-function mutation in the GNAS1 gene leading to increased intracellular cAMP
. Mutation in the FGFR3 gene causing constitutive activation of the receptor
. Defect in the CBFA1 (RUNX2) transcription factor affecting osteoblast differentiation
. Somatic mosaic mutation in the IDH1 gene leading to oncometabolite production

Correct Answer & Explanation

. Gain-of-function mutation in the GNAS1 gene leading to increased intracellular cAMP

Explanation

Correct Answer: Gain-of-function mutation in the GNAS1 gene leading to increased intracellular cAMPThis patient presents with classic signs of McCune-Albright syndrome (polyostotic fibrous dysplasia, 'coast of Maine' cafe-au-lait spots, and endocrine abnormalities). Fibrous dysplasia is caused by a somatic, gain-of-function mutation in the GNAS1 gene. This mutation affects the alpha subunit of the stimulatory G protein (Gs-alpha), leading to constitutive activation of adenylate cyclase and elevated intracellular cyclic AMP (cAMP). This anarchic development results in the replacement of normal bone with fibrous stroma and immature woven bone. EXT1 mutations cause Multiple Hereditary Exostoses. FGFR3 mutations cause Achondroplasia. CBFA1 mutations cause Cleidocranial Dysplasia. IDH1/2 mutations cause Enchondromatosis (Ollier/Maffucci).

Question 853

Topic: Bone Tumors

A 7-year-old girl is diagnosed with Ollier disease after presenting with multiple enchondromas predominantly affecting the right side of her body. Which of the following statements regarding the genetics and transmission of her condition is most accurate?

. It is inherited in an autosomal dominant pattern with incomplete penetrance
. It is caused by a germline mutation in the EXT1 gene
. It results from somatic mosaic mutations in the IDH1 or IDH2 genes and is not inherited
. It is an X-linked recessive disorder affecting primarily males
. It is caused by a somatic mutation in the GNAS gene

Correct Answer & Explanation

. It results from somatic mosaic mutations in the IDH1 or IDH2 genes and is not inherited

Explanation

Correct Answer: It results from somatic mosaic mutations in the IDH1 or IDH2 genes and is not inheritedOllier disease (enchondromatosis) is a non-hereditary disorder characterized by the anarchic development of multiple enchondromas, often with a unilateral predominance. It is caused by somatic mosaic mutations in the isocitrate dehydrogenase 1 (IDH1) or IDH2 genes. Because it is a somatic mosaicism occurring post-zygotically, it is not passed from parent to child. GNAS somatic mutations cause Fibrous Dysplasia. EXT1/EXT2 germline mutations cause Multiple Hereditary Exostoses (autosomal dominant).

Question 854

Topic: Bone Tumors

A 45-year-old female with known polyostotic fibrous dysplasia presents with a painless, slow-growing soft tissue mass in her right thigh. MRI reveals a well-circumscribed intramuscular lesion with high T2 signal intensity. Biopsy confirms an intramuscular myxoma. This combination of findings is pathognomonic for which of the following syndromes?

. McCune-Albright syndrome
. Mazabraud syndrome
. Maffucci syndrome
. Jaffe-Campanacci syndrome
. Klippel-Trenaunay syndrome

Correct Answer & Explanation

. Mazabraud syndrome

Explanation

Correct Answer: Mazabraud syndromeMazabraud syndrome is a rare disorder characterized by the association of fibrous dysplasia (usually polyostotic) and one or multiple intramuscular myxomas. The myxomas typically occur in the same anatomic region as the most severely affected bones. McCune-Albright syndrome involves fibrous dysplasia, cafe-au-lait spots, and endocrinopathies. Maffucci syndrome involves enchondromas and hemangiomas. Jaffe-Campanacci syndrome involves multiple non-ossifying fibromas and cafe-au-lait spots.

Question 855

Topic: Bone Tumors

A 4-year-old boy presents with an asymmetric, painless swelling on the medial aspect of his right ankle. Radiographs show an irregular, ossified mass arising from the medial epiphysis of the distal tibia. The condition is characterized by an anarchic overgrowth of epiphyseal cartilage. What is the most likely diagnosis?

. Multiple Epiphyseal Dysplasia
. Chondrodysplasia Punctata
. Dysplasia Epiphysealis Hemimelica (Trevor disease)
. Spondyloepiphyseal Dysplasia Tarda
. 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 asymmetric, anarchic overgrowth of cartilage at the epiphysis (essentially an intra-articular osteochondroma). It most commonly affects the medial side of the epiphyses in the lower extremities (ankle or knee) of young children. Multiple Epiphyseal Dysplasia presents with symmetric, delayed, and irregular ossification of multiple epiphyses. Ollier disease involves the metaphyses and diaphyses (enchondromas), not primarily an epiphyseal overgrowth.

Question 856

Topic: Bone Tumors

A 6-year-old girl is brought to the orthopedic clinic with a limp and a radiographically confirmed fibrous dysplasia lesion in her proximal femur. Physical examination reveals a large cafe-au-lait macule with irregular 'coast of Maine' borders on her trunk. If this patient has McCune-Albright syndrome, which of the following is the most common endocrine abnormality she is likely to experience?

. Hyperthyroidism
. Cushing syndrome
. Precocious puberty
. Acromegaly
. Hyperparathyroidism

Correct Answer & Explanation

. Precocious puberty

Explanation

Correct Answer: Precocious pubertyMcCune-Albright syndrome is defined by the triad of polyostotic fibrous dysplasia, cafe-au-lait macules, and autonomous endocrine hyperfunction. The most common endocrine manifestation, particularly in females, is gonadotropin-independent precocious puberty, caused by autonomous ovarian cyst formation and estrogen production. While hyperthyroidism, Cushing syndrome, and growth hormone excess (leading to acromegaly/gigantism) can also occur due to the underlying GNAS mutation affecting various endocrine glands, precocious puberty is by far the most frequent.

Question 857

Topic: Bone Tumors

A 14-year-old girl with polyostotic fibrous dysplasia presents with a progressive 'shepherd's crook' deformity of the proximal femur. Surgical correction with valgus osteotomy is planned. Which of the following grafting techniques is most appropriate to minimize the risk of graft resorption and recurrence?

. Cancellous autograft
. Cortical allograft
. Demineralized bone matrix (DBM)
. Synthetic hydroxyapatite

Correct Answer & Explanation

. Cortical allograft

Explanation

Correct Answer: Cortical allograftIn the surgical management of fibrous dysplasia, particularly for structural deformities like the shepherd's crook deformity of the proximal femur, cortical allograft is the preferred graft material. Cancellous autograft is rapidly resorbed and replaced by the dysplastic fibrous tissue, leading to a high rate of recurrence. Cortical allografts resist resorption much better and provide the necessary structural support while incorporating slowly.

Question 858

Topic: Bone Tumors

Which of the following genetic mutations is most strongly associated with the development of Ollier disease?

. EXT1
. GNAS
. IDH1
. LEMD3

Correct Answer & Explanation

. IDH1

Explanation

Correct Answer: IDH1Ollier disease (enchondromatosis) and Maffucci syndrome are associated with somatic mosaic mutations in the isocitrate dehydrogenase 1 (IDH1) or IDH2 genes. These mutations lead to the production of the oncometabolite D-2-hydroxyglutarate, which interferes with normal chondrocyte differentiation. EXT1 is associated with multiple hereditary exostoses, GNAS with fibrous dysplasia, and LEMD3 with osteopoikilosis.

Question 859

Topic: Bone Tumors
A 7-year-old girl is diagnosed with McCune-Albright syndrome. In addition to polyostotic fibrous dysplasia and characteristic café-au-lait macules, which of the following is the most common endocrinopathy seen in this condition?
. Hyperparathyroidism
. Precocious puberty
. Diabetes insipidus
. Adrenal insufficiency

Correct Answer & Explanation

. Precocious puberty

Explanation

McCune-Albright syndrome is defined by the triad of polyostotic fibrous dysplasia, café-au-lait spots (typically with irregular 'Coast of Maine' borders), and autonomous endocrine hyperfunction. The most common endocrinopathy, particularly in females, is gonadotropin-independent precocious puberty. Other possible endocrine abnormalities include hyperthyroidism, growth hormone excess (acromegaly/gigantism), and Cushing syndrome.

Question 860

Topic: Bone Tumors

Which of the following genetic mutations is most commonly shared in the pathogenesis of both Ollier disease and Maffucci syndrome?

. EXT1
. GNAS1
. IDH1
. LEMD3
. COMP

Correct Answer & Explanation

. IDH1

Explanation

Correct Answer: C (IDH1)Ollier disease (multiple enchondromatosis) and Maffucci syndrome (multiple enchondromatosis associated with soft-tissue hemangiomas) are both non-hereditary skeletal dysplasias. Recent genetic studies have identified somatic mosaic mutations in the isocitrate dehydrogenase 1 (IDH1) and IDH2 genes as the primary drivers in both conditions. EXT1 is associated with Multiple Hereditary Exostoses, GNAS1 with Fibrous Dysplasia, LEMD3 with Melorheostosis and Osteopoikilosis, and COMP with Pseudoachondroplasia.

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