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10. Pathology and Oncology MCQs

Practice Set 315 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 6281

Topic: 10. Pathology and Oncology

A patient is evaluated for surgical stabilization of an impending pathologic femur fracture due to metastatic disease. Among the following options, which primary tumor generally carries the most favorable long-term survival prognosis after bony metastasis?

. Lung carcinoma
. Pancreatic adenocarcinoma
. Thyroid carcinoma
. Hepatocellular carcinoma
. Melanoma

Correct Answer & Explanation

. Thyroid carcinoma

Explanation

Among the common bone-metastasizing carcinomas, thyroid and breast cancer carry relatively favorable long-term prognoses even after skeletal dissemination. Conversely, lung and gastrointestinal primaries with bone metastases carry very poor survival rates.

Question 6282

Topic: 10. Pathology and Oncology

When surgically managing an impending pathologic fracture of the femoral shaft due to metastatic breast cancer

, which biomechanical principle must guide the choice of implant?

. The fixation should precisely span only 2 centimeters above and below the visible lesion.
. The implant must be load-bearing and span the entire length of the bone to protect against future metastases.
. Rigid dual-plate fixation is required to counteract rotational instability completely.
. Polymethylmethacrylate (PMMA) should never be used because it inhibits the local immune response.
. Resection of the entire diaphysis with an endoprosthetic replacement is mandatory.

Correct Answer & Explanation

. The implant must be load-bearing and span the entire length of the bone to protect against future metastases.

Explanation

In the management of long bone metastases, intramedullary nails are preferred as they are load-sharing devices that protect the entire bone. This prevents subsequent failure if new metastatic lesions develop in the same bone.

Question 6283

Topic: 10. Pathology and Oncology

Which of the following is the primary pathophysiologic mechanism underlying primary synovial chondromatosis?

. Benign neoplastic proliferation of articular chondrocytes
. Synovial metaplasia resulting in cartilaginous nodule formation
. Degenerative fragmentation of articular cartilage due to trauma
. Inflammatory response to recurrent intra-articular hemorrhage
. Genetic mutation in the EXT1 gene leading to exostoses

Correct Answer & Explanation

. Synovial metaplasia resulting in cartilaginous nodule formation

Explanation

Primary synovial chondromatosis is characterized by benign metaplasia of the synovial membrane, which forms cartilaginous nodules. These nodules can eventually detach, calcify, and become free-floating loose bodies within the joint space.

Question 6284

Topic: 10. Pathology and Oncology

A 45-year-old male with a long-standing history of recurrent synovial chondromatosis of the knee presents with sudden, rapidly increasing pain and swelling. MRI reveals a large soft tissue mass eroding into the distal femur. What is the most likely diagnosis?

. Pigmented villonodular synovitis
. Secondary chondrosarcoma
. Osteosarcoma
. Synovial sarcoma
. Myxoid liposarcoma

Correct Answer & Explanation

. Secondary chondrosarcoma

Explanation

Malignant transformation of primary synovial chondromatosis to secondary chondrosarcoma is rare, occurring in about 5% of cases. It should be strongly suspected when there is rapid clinical deterioration, severe pain, or aggressive bone erosion.

Question 6285

Topic: 10. Pathology and Oncology

When evaluating a patient with metastatic bone disease of the femur, which of the following factors would contribute the highest point value in Mirels' scoring system for prophylactic fixation?

. Blastic lesion appearance
. Lesion size less than 1/3 of the bone cortex
. Mild pain relieved by rest
. Upper extremity location
. Purely lytic lesion appearance

Correct Answer & Explanation

. Purely lytic lesion appearance

Explanation

In Mirels' criteria, a lytic lesion scores the maximum 3 points for the 'radiographic appearance' category, whereas a mixed lesion scores 2, and a blastic lesion scores 1. A total score of 9 or greater strongly indicates the need for prophylactic internal fixation.

Question 6286

Topic: Bone Tumors

Which histological feature helps differentiate primary synovial chondromatosis from secondary synovial chondromatosis?

. Presence of bone formation within the nodules
. Cellular atypia, hypercellularity, and binucleated chondrocytes
. Extensive acute inflammatory infiltrates
. Concentric rings of ossification without atypia
. Abundant multinucleated giant cells

Correct Answer & Explanation

. Cellular atypia, hypercellularity, and binucleated chondrocytes

Explanation

Primary synovial chondromatosis often exhibits hypercellularity, cellular atypia, pleomorphism, and binucleated chondrocytes, which can easily mimic a low-grade chondrosarcoma. Secondary chondromatosis typically shows mature cartilage with rings of ossification and lacks significant atypia.

Question 6287

Topic: Bone Tumors
A 9-year-old girl presents with a limp and a shepherd's crook deformity of the proximal femur. She also has large, irregularly bordered hyperpigmented skin macules. What endocrine abnormality is most commonly associated with this syndrome?
. Hypothyroidism
. Precocious puberty
. Hyperparathyroidism
. Adrenal insufficiency
. Diabetes insipidus

Correct Answer & Explanation

. Precocious puberty

Explanation

The presentation describes McCune-Albright syndrome, which consists of polyostotic fibrous dysplasia, café-au-lait spots (Coast of Maine borders), and hyperfunctioning endocrinopathies. Precocious puberty is the most common endocrine manifestation.

Question 6288

Topic: 10. Pathology and Oncology

A 65-year-old male presents with a purely blastic metastatic lesion in his lumbar spine. Which primary malignancy is the most likely source?

. Renal cell carcinoma
. Thyroid carcinoma
. Multiple myeloma
. Prostate carcinoma
. Lung carcinoma

Correct Answer & Explanation

. Prostate carcinoma

Explanation

Prostate cancer metastases to the bone are characteristically osteoblastic. In contrast, renal cell carcinoma, thyroid carcinoma, and multiple myeloma typically present with purely lytic bone lesions.

Question 6289

Topic: Bone Tumors

A routine radiograph of a 25-year-old patient reveals an expansile, intramedullary lesion in the proximal femur with a hazy, 'ground-glass' appearance and endosteal scalloping. What is the recommended surgical management if the lesion is completely asymptomatic and structurally stable?

. Curettage and bone grafting with allograft
. Prophylactic intramedullary nailing
. En bloc resection and endoprosthetic reconstruction
. Observation with serial radiographs
. Intralesional corticosteroid injection

Correct Answer & Explanation

. Observation with serial radiographs

Explanation

Asymptomatic, structurally stable fibrous dysplasia lesions are typically managed with observation. Curettage and grafting generally fail because the graft is resorbed and rapidly replaced by dysplastic host tissue.

Question 6290

Topic: 10. Pathology and Oncology

A patient with a known history of renal cell carcinoma requires intramedullary nailing for an impending pathologic fracture of the femur. Which preoperative intervention is strongly recommended?

. Neoadjuvant chemotherapy
. Preoperative selective arterial embolization
. Prophylactic inferior vena cava filter placement
. Local bisphosphonate injection
. Systemic heparinization

Correct Answer & Explanation

. Preoperative selective arterial embolization

Explanation

Metastatic bone lesions from renal cell and thyroid carcinomas are extremely vascular. Preoperative selective arterial embolization 24-48 hours before surgery is highly recommended to minimize massive, potentially life-threatening intraoperative blood loss.

Question 6291

Topic: 10. Pathology and Oncology

A 12-year-old girl presents with a persistent limp. Radiographs demonstrate an expansile proximal femur lesion with a "ground-glass" appearance.

What is the underlying molecular pathogenesis of this condition?

. Mutation in EXT1 leading to disrupted heparan sulfate
. Activating mutation in the GNAS gene leading to increased cAMP
. Inactivating mutation of the RB1 tumor suppressor gene
. Mutation in COL1A1 affecting type I collagen production
. Overexpression of the c-Fos proto-oncogene

Correct Answer & Explanation

. Activating mutation in the GNAS gene leading to increased cAMP

Explanation

Fibrous dysplasia is caused by a somatic, activating missense mutation in the GNAS gene. This leads to increased intracellular cAMP, causing abnormal proliferation and differentiation of osteoblasts. The characteristic radiographic finding is a "ground-glass" matrix.

Question 6292

Topic: 10. Pathology and Oncology

A 40-year-old male presents with mechanical knee pain, clicking, and intermittent locking. MRI shows multiple intra-articular loose bodies of uniform size with a "ring and arc" enhancement pattern. What is the primary histological process driving this condition?

. Synovial hyperplasia secondary to crystalline deposition
. Benign metaplasia of the synovium into hyaline cartilage
. Osteophytic fragmentation due to advanced osteoarthritis
. Malignant transformation of resident articular chondrocytes
. Hypertrophy and ossification of the infrapatellar fat pad

Correct Answer & Explanation

. Benign metaplasia of the synovium into hyaline cartilage

Explanation

Primary synovial chondromatosis involves the benign metaplasia of synovial lining cells into hyaline cartilage nodules. These nodules can detach to form loose bodies that may subsequently calcify or ossify. Unlike secondary chondromatosis, the loose bodies in the primary form are typically uniform in size.

Question 6293

Topic: 10. Pathology and Oncology

A 62-year-old female with known breast cancer presents with moderate thigh pain. Radiographs reveal a lytic lesion in the femoral diaphysis involving 75% of the cortical diameter.

According to Mirels' criteria, what is her score and the most appropriate recommendation?

. Score 7; Radiation therapy alone is indicated
. Score 8; Marginal indication, observation with bisphosphonates
. Score 9; Protected weight bearing and close observation
. Score 10; Prophylactic internal fixation is highly recommended
. Score 11; Resection and endoprosthetic reconstruction is required

Correct Answer & Explanation

. Score 10; Prophylactic internal fixation is highly recommended

Explanation

The Mirels score dictates fracture risk based on site, pain, lesion type, and size. Lower extremity (2), moderate pain (2), lytic nature (3), and size >2/3 cortex (3) yields a score of 10. A score of 9 or greater is a strong indication for prophylactic fixation.

Question 6294

Topic: 10. Pathology and Oncology

A 35-year-old female with known polyostotic fibrous dysplasia presents with a painless, deep-seated soft tissue mass in her right thigh.

Excisional biopsy of the mass reveals an intramuscular myxoma. Which syndrome is this patient exhibiting?

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

Correct Answer & Explanation

. Mazabraud syndrome

Explanation

Mazabraud syndrome is a rare condition characterized by the association of fibrous dysplasia (usually polyostotic) with single or multiple intramuscular myxomas. The myxomas typically occur in the same anatomic region as the bony lesions.

Question 6295

Topic: 10. Pathology and Oncology

A 68-year-old male with a history of renal cell carcinoma presents with a solitary lytic metastasis in the proximal humerus and an impending fracture.

What is an essential step prior to surgical stabilization of this lesion?

. Neoadjuvant systemic chemotherapy
. Preoperative selective arterial embolization
. Core needle biopsy in the operating room prior to incision
. Prophylactic irradiation of the entire humerus
. Administration of denosumab 24 hours prior to surgery

Correct Answer & Explanation

. Preoperative selective arterial embolization

Explanation

Metastases from renal cell carcinoma and thyroid carcinoma are notoriously hypervascular. Preoperative selective arterial embolization within 24 to 48 hours of surgery is critical to minimize massive intraoperative blood loss.

Question 6296

Topic: 10. Pathology and Oncology

A 50-year-old male with a long-standing history of primary synovial chondromatosis of the hip presents with acute worsening of pain and rapid joint swelling. MRI demonstrates a new, aggressive soft tissue mass with marrow invasion. What is the most likely diagnosis?

. Septic arthritis
. Pigmented villonodular synovitis (PVNS)
. Secondary chondrosarcoma
. Synovial sarcoma
. Osteosarcoma

Correct Answer & Explanation

. Secondary chondrosarcoma

Explanation

Malignant transformation of primary synovial chondromatosis into secondary chondrosarcoma occurs in approximately 5% of cases. Rapid clinical deterioration, new aggressive mass, and marrow invasion on MRI are highly suspicious for this transformation.

Question 6297

Topic: Bone Tumors

A 22-year-old male with polyostotic fibrous dysplasia presents with a severe Shepherd's crook deformity of the proximal femur.

When planning corrective osteotomy and fixation, which biomechanical principle is most critical to prevent mechanical failure?

. Use of a sliding hip screw with extensive cancellous bone graft
. Use of a load-sharing intramedullary device spanning the entire femur
. Curettage and isolated cortical strut allografting
. Total hip arthroplasty using a cemented stem
. External fixation with progressive distraction osteogenesis

Correct Answer & Explanation

. Use of a load-sharing intramedullary device spanning the entire femur

Explanation

In the surgical treatment of fibrous dysplasia deformities (like Shepherd's crook), intramedullary nailing spanning the entire length of the bone is required. Plates and screws have an unacceptably high failure rate because the abnormal host bone cannot adequately hold screws or share loads.

Question 6298

Topic: 10. Pathology and Oncology

A 45-year-old male with a long-standing history of primary synovial chondromatosis of the hip presents with acutely worsening pain and rapid swelling. Radiographs show new cortical erosion and marrow involvement. Which of the following is the most likely diagnosis?

. Osteosarcoma
. Synovial sarcoma
. Secondary chondrosarcoma
. Malignant fibrous histiocytoma
. Chondroblastoma

Correct Answer & Explanation

. Secondary chondrosarcoma

Explanation

Primary synovial chondromatosis carries a rare but recognized risk (1-5%) of malignant transformation to secondary chondrosarcoma. Clinical clues include rapid worsening of symptoms, marrow invasion, and new cortical erosion on imaging.

Question 6299

Topic: 10. Pathology and Oncology

When evaluating a patient with a metastatic lesion to the long bone, the Mirels' scoring system is used to predict the risk of pathologic fracture. Which of the following combinations yields the highest score (3 points) for each respective category?

. Upper extremity, mild pain, blastic lesion, <1/3 cortical width
. Lower extremity, moderate pain, mixed lesion, 1/3 to 2/3 cortical width
. Peritrochanteric region, functional pain, lytic lesion, >2/3 cortical width
. Upper extremity, functional pain, lytic lesion, 1/3 to 2/3 cortical width
. Peritrochanteric region, mild pain, blastic lesion, >2/3 cortical width

Correct Answer & Explanation

. Peritrochanteric region, functional pain, lytic lesion, >2/3 cortical width

Explanation

Mirels' criteria assign 3 points for: peritrochanteric location, functional (mechanical) pain, purely lytic nature, and size >2/3 of the cortical diameter. A total score of 9 or greater is a strong indication for prophylactic surgical fixation.

Question 6300

Topic: Bone Tumors

A 9-year-old girl presents with a limp and a history of early-onset puberty. Radiographs reveal multiple expansile ground-glass lesions in the femur and tibia. Physical exam notes large, irregular hyperpigmented skin macules. What is the classic term for these skin lesions?

. Coast of California spots
. Coast of Maine spots
. Ash-leaf spots
. Shagreen patches
. Lisch nodules

Correct Answer & Explanation

. Coast of Maine spots

Explanation

The patient has McCune-Albright syndrome, characterized by the triad of polyostotic fibrous dysplasia, precocious puberty, and cafe-au-lait spots. The cafe-au-lait spots in this syndrome have irregular borders, classically described as the 'Coast of Maine', unlike the smooth 'Coast of California' spots seen in neurofibromatosis.

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