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10. Pathology and Oncology MCQs

Practice Set 316 of 351

This practice set contains high-yield board review questions covering key concepts in 10. Pathology and Oncology. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 6301

Topic: 10. Pathology and Oncology

Primary synovial chondromatosis is fundamentally a disease driven by which of the following pathophysiological processes?

. Reactive synovial inflammation due to mechanical wear and tear
. Infection by atypical mycobacteria leading to granuloma formation
. Benign neoplastic metaplasia of the synovial membrane
. Autoimmune destruction of articular cartilage
. Deposition of calcium pyrophosphate dihydrate crystals

Correct Answer & Explanation

. Benign neoplastic metaplasia of the synovial membrane

Explanation

Primary synovial chondromatosis is a benign neoplastic process characterized by cartilaginous metaplasia of the synovial membrane. The metaplastic tissue forms nodular hyaline cartilage masses that can detach and become loose bodies within the joint space.

Question 6302

Topic: 10. Pathology and Oncology

A 62-year-old male presents with a purely lytic impending pathologic fracture of the proximal femur secondary to metastatic renal cell carcinoma. Before proceeding with prophylactic intramedullary nailing, what critical step should be taken to minimize perioperative complications?

. Administration of high-dose intravenous bisphosphonates
. Preoperative radiation therapy to the entire femur
. Preoperative angiographic embolization of the lesion
. Neoadjuvant systemic chemotherapy
. Bone marrow biopsy of the contralateral iliac crest

Correct Answer & Explanation

. Preoperative angiographic embolization of the lesion

Explanation

Renal cell carcinoma and thyroid carcinoma bone metastases are notoriously hypervascular. Preoperative selective arterial embolization is highly recommended 24 to 48 hours prior to surgery to minimize life-threatening intraoperative hemorrhage.

Question 6303

Topic: Bone Tumors

A 25-year-old patient with polyostotic fibrous dysplasia presents with increasing hip pain and a progressive varus deformity of the proximal femur. What is the most appropriate surgical management for this characteristic "shepherd's crook" deformity?

. Curettage and bone grafting with cancellous allograft
. Valgus-producing osteotomy and load-sharing intramedullary nail fixation
. Total hip arthroplasty
. Proximal femoral resection and endoprosthetic reconstruction
. Observation and intravenous bisphosphonate therapy

Correct Answer & Explanation

. Valgus-producing osteotomy and load-sharing intramedullary nail fixation

Explanation

The shepherd's crook deformity in fibrous dysplasia requires correction of the mechanical axis via a valgus osteotomy, followed by load-sharing intramedullary fixation to bypass the entire abnormal bone segment. Cancellous bone grafts should be avoided as they resorb and are rapidly replaced by dysplastic host bone.

Question 6304

Topic: 10. Pathology and Oncology

A 45-year-old man with a known history of primary synovial chondromatosis of the hip presents with sudden, rapidly progressive pain and a new palpable mass. Plain radiographs demonstrate cortical destruction and extension into the surrounding soft tissues. Which of the following is the most reliable histologic indicator of malignant transformation in this condition?

. Presence of binucleate chondrocytes
. Hypercellularity and nuclear pleomorphism
. Invasion of marrow spaces by chondrocytes
. Clustering of chondrocytes in hyaline cartilage
. Calcification within the cartilaginous nodules

Correct Answer & Explanation

. Invasion of marrow spaces by chondrocytes

Explanation

Malignant transformation of primary synovial chondromatosis to chondrosarcoma is rare. Because primary synovial chondromatosis naturally exhibits cellular atypia, binucleation, and hypercellularity, marrow invasion remains the most reliable hallmark of malignant transformation.

Question 6305

Topic: 10. Pathology and Oncology

Primary synovial chondromatosis is a benign neoplastic process rather than a purely reactive metaplasia. Which of the following cytogenetic abnormalities is most frequently associated with the primary form of this disease?

. t(11;22) EWSR1-FLI1
. t(X;18) SYT-SSX
. t(12;16) FUS-DDIT3
. Chromosome 6 alterations and FN1-ACVR2A fusions
. GNAS1 point mutations

Correct Answer & Explanation

. Chromosome 6 alterations and FN1-ACVR2A fusions

Explanation

Primary synovial chondromatosis is a benign clonal neoplasm often associated with chromosome 6p21 abnormalities or FN1-ACVR2A gene fusions. The other options refer to Ewing sarcoma, synovial sarcoma, myxoid liposarcoma, and fibrous dysplasia, respectively.

Question 6306

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with progressive bowing and pain in his right femur. Radiographs display an expansile ground-glass lesion in the diaphysis. Biopsy confirms fibrous dysplasia. What is the precise genetic etiology of this condition?

. Post-zygotic somatic mutation in the GNAS gene
. Germline mutation in the GNAS gene
. Somatic mutation in the EXT1 gene
. Germline mutation in the PTEN gene
. Post-zygotic somatic mutation in the VHL gene

Correct Answer & Explanation

. Post-zygotic somatic mutation in the GNAS gene

Explanation

Fibrous dysplasia is caused by a post-zygotic somatic activating mutation in the GNAS gene. This leads to constitutive activation of the Gs-alpha protein and increased intracellular cAMP, disrupting normal osteoblast differentiation.

Question 6307

Topic: 10. Pathology and Oncology

A 65-year-old man with a history of radical nephrectomy presents with severe right thigh pain. Radiographs reveal a large, impending pathologic fracture of the proximal femur due to a lytic lesion. What is the most critical intervention to perform prior to intramedullary nailing?

. Administration of denosumab
. Preoperative angiography and embolization
. Prophylactic irradiation of the femur
. Administration of high-dose systemic corticosteroids
. Open incisional biopsy

Correct Answer & Explanation

. Preoperative angiography and embolization

Explanation

Metastatic renal cell carcinoma lesions are notoriously hypervascular. Preoperative angiography and embolization are highly recommended to minimize life-threatening intraoperative hemorrhage during internal fixation.

Question 6308

Topic: Bone Tumors

A 25-year-old woman with known fibrous dysplasia presents with increasing thigh pain and a progressive shepherd's crook deformity. What is the most appropriate surgical management to address her symptoms and deformity?

. Curettage and autologous cancellous bone grafting
. Valgus osteotomy and rigid plate fixation
. Valgus osteotomy and intramedullary nailing
. Intravenous bisphosphonate therapy alone
. En bloc resection and endoprosthetic reconstruction

Correct Answer & Explanation

. Valgus osteotomy and intramedullary nailing

Explanation

Surgical management of a shepherd's crook deformity involves valgus producing osteotomies stabilized with intramedullary nailing. Plate fixation is prone to failure due to the poor quality of dysplastic bone, and cancellous bone grafts are rapidly resorbed.

Question 6309

Topic: 10. Pathology and Oncology

A 50-year-old woman with metastatic breast cancer presents with a newly discovered lytic lesion in the peritrochanteric region of her femur. The lesion involves 50% of the cortical diameter. She reports severe pain with weight-bearing. What is her Mirels' score?

. 7
. 8
. 9
. 11
. 12

Correct Answer & Explanation

. 11

Explanation

Mirels' criteria scores: Site (Peritrochanteric = 3), Pain (Severe = 3), Lesion type (Lytic = 3), and Size (1/3 to 2/3 = 2). The total score is 3+3+3+2 = 11, indicating a high risk of fracture requiring prophylactic fixation.

Question 6310

Topic: 10. Pathology and Oncology

A 50-year-old man with long-standing primary synovial chondromatosis of the hip presents with rapid worsening of pain and swelling. MRI reveals a new, large soft tissue mass invading the adjacent marrow cavity with cortical destruction. What is the most likely diagnosis?

. Osteosarcoma
. Chondrosarcoma
. Synovial sarcoma
. Fibrosarcoma
. Giant cell tumor of bone

Correct Answer & Explanation

. Chondrosarcoma

Explanation

Primary synovial chondromatosis carries a rare but documented risk (approx 5%) of malignant transformation into secondary chondrosarcoma. Rapid progression and marrow invasion are classic radiologic signs of this transformation.

Question 6311

Topic: Bone Tumors

A 35-year-old female is diagnosed with polyostotic fibrous dysplasia. During her workup, an MRI of her thigh unexpectedly reveals multiple well-circumscribed, T2-hyperintense soft tissue masses within her skeletal muscle. What is the correct diagnosis for this presentation?

. McCune-Albright syndrome
. Mazabraud syndrome
. Jaffe-Campanacci syndrome
. Ollier disease
. Maffucci syndrome

Correct Answer & Explanation

. Mazabraud syndrome

Explanation

Mazabraud syndrome is the rare combination of polyostotic fibrous dysplasia and multiple intramuscular myxomas. The myxomas are typically benign and appear hyperintense on T2-weighted MRI.

Question 6312

Topic: 10. Pathology and Oncology

A 72-year-old man with metastatic prostate cancer has multiple dense, osteoblastic lesions in his lumbar spine and pelvis. Which of the following factors, secreted by the tumor cells, is primarily responsible for the osteoblastic nature of these metastases?

. Parathyroid hormone-related peptide (PTHrP)
. Receptor activator of nuclear factor kappa-B ligand (RANKL)
. Endothelin-1
. Interleukin-6
. Tumor necrosis factor-alpha

Correct Answer & Explanation

. Endothelin-1

Explanation

Prostate cancer metastases are classically osteoblastic. This is primarily mediated by the secretion of Endothelin-1, which stimulates osteoblast proliferation and bone formation.

Question 6313

Topic: Bone Tumors

Which classic histologic feature clearly distinguishes fibrous dysplasia from normal bone and other reactive fibro-osseous lesions?

. Prominent osteoblastic rimming of thickened trabeculae
. Irregular woven bone trabeculae lacking osteoblastic rimming
. Presence of multinucleated giant cells in a hemorrhagic background
. Nests of atypical chondrocytes with binucleation
. Sheets of plasma cells with eccentric nuclei

Correct Answer & Explanation

. Irregular woven bone trabeculae lacking osteoblastic rimming

Explanation

Fibrous dysplasia is histologically characterized by irregular, "Chinese character" shaped trabeculae of woven bone that arise directly from a fibrous stroma without normal osteoblastic rimming.

Question 6314

Topic: 10. Pathology and Oncology



A 60-year-old woman presents with a destructive humeral diaphyseal lesion. Biopsy confirms metastatic follicular thyroid carcinoma. What defines the most appropriate operative strategy for this patient?

. Curettage and cementation alone without instrumentation
. Preoperative angiography with embolization followed by intramedullary nailing
. Primary amputation due to high risk of massive hemorrhage
. Administration of high-dose local radiotherapy prior to plate fixation
. Initiation of bisphosphonates without surgical intervention

Correct Answer & Explanation

. Preoperative angiography with embolization followed by intramedullary nailing

Explanation

Metastatic thyroid carcinoma is highly vascular. Preoperative embolization is heavily recommended to limit intraoperative blood loss prior to stabilization, which is best achieved with intramedullary nailing in diaphyseal lesions.

Question 6315

Topic: 10. Pathology and Oncology

Primary synovial chondromatosis is considered a benign neoplastic process. Which of the following genetic fusions or chromosomal abnormalities is frequently implicated in its pathogenesis?

. t(11;22) EWSR1-FLI1
. t(X;18) SYT-SSX
. t(12;16) FUS-DDIT3
. FN1-ACVR2A fusion
. COL1A1-PDGFB fusion

Correct Answer & Explanation

. FN1-ACVR2A fusion

Explanation

Primary synovial chondromatosis has been shown to harbor recurrent FN1-ACVR2A fusions and abnormalities in chromosome 6p21, confirming it as a benign neoplastic process rather than simply a reactive metaplasia.

Question 6316

Topic: Bone Tumors

A 24-year-old with polyostotic fibrous dysplasia presents with a progressively painful Shepherd's crook deformity of the proximal femur.

If surgical intervention is elected to correct the deformity and prevent fracture, which of the following is the most appropriate biomechanical and biological strategy?

. Valgus osteotomy with cancellous bone grafting and plate fixation
. Intramedullary nailing with or without cortical bone grafting
. Curettage and cementation with prophylactic plate fixation
. Resection and endoprosthetic reconstruction
. Observation and initiation of denosumab therapy

Correct Answer & Explanation

. Intramedullary nailing with or without cortical bone grafting

Explanation

Fibrous dysplasia replaces normal bone with weak woven bone. Cancellous bone grafts are consistently resorbed by the host dysplastic tissue, so cortical allografts or intramedullary devices spanning the entire bone are required for durable fixation.

Question 6317

Topic: 10. Pathology and Oncology

A 45-year-old male with a long-standing history of primary synovial chondromatosis of the hip presents with acute worsening of pain and a rapidly enlarging mass. Which of the following is the most reliable histologic or clinical indicator of malignant transformation to secondary chondrosarcoma in this specific setting?

. Cellular atypia and binucleate cells
. Presence of hyaline cartilage nodules
. Invasion of the bone marrow cavity or extra-articular soft tissues
. Endochondral ossification within the loose bodies
. Hypercellularity of the synovial lining

Correct Answer & Explanation

. Invasion of the bone marrow cavity or extra-articular soft tissues

Explanation

Primary synovial chondromatosis inherently demonstrates significant cellular atypia and binucleate cells, mimicking malignancy. Therefore, true tissue invasion into the marrow or surrounding structures is the most reliable criterion for diagnosing malignant transformation to chondrosarcoma.

Question 6318

Topic: 10. Pathology and Oncology

A 62-year-old man presents with a pathologic fracture of the proximal humerus secondary to a metastatic renal cell carcinoma lesion.

Prior to surgical stabilization, which of the following interventions is most strongly recommended to minimize intraoperative morbidity?

. Administration of high-dose denosumab
. Preoperative prophylactic radiation therapy
. Preoperative selective arterial embolization
. Initiation of intravenous bisphosphonates
. Neoadjuvant targeted immunotherapy

Correct Answer & Explanation

. Preoperative selective arterial embolization

Explanation

Bone metastases from renal cell carcinoma and thyroid cancer are highly vascular. Preoperative selective arterial embolization (typically 24-48 hours before surgery) is strongly recommended to significantly reduce the risk of massive, life-threatening intraoperative hemorrhage.

Question 6319

Topic: Bone Tumors
A 9-year-old girl is evaluated for precocious puberty and café-au-lait spots with irregular "coast of Maine" borders. Radiographs of her lower extremities demonstrate multiple lucent, ground-glass bone lesions. Which of the following best describes the underlying genetic anomaly in this patient?
. Germline mutation in the EXT1 gene
. Post-zygotic somatic mutation of the GNAS gene
. Germline mutation of the GNAS gene
. Defect in the COL1A1 gene
. Mutation in the FGFR3 gene

Correct Answer & Explanation

. Post-zygotic somatic mutation of the GNAS gene

Explanation

This patient presents with McCune-Albright syndrome (polyostotic fibrous dysplasia, endocrinopathy, café-au-lait spots). It is caused by a post-zygotic somatic missense mutation in the GNAS gene; a germline mutation of this gene is lethal.

Question 6320

Topic: 10. Pathology and Oncology

A 35-year-old woman with known polyostotic fibrous dysplasia presents with a painless, deep-seated soft tissue mass in her right thigh. Biopsy of the mass reveals an intramuscular myxoma. This patient is at an increased risk of developing which of the following?

. Osteosarcoma
. Thyroid carcinoma
. Pituitary adenoma
. Chondrosarcoma
. Ewing sarcoma

Correct Answer & Explanation

. Osteosarcoma

Explanation

Mazabraud syndrome is the rare association of polyostotic fibrous dysplasia with intramuscular myxomas. These patients have a significantly higher risk of malignant transformation of their bone lesions, most commonly to osteosarcoma.

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