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10. Pathology and Oncology MCQs

Practice Set 118 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 2341

Topic: 10. Pathology and Oncology

An examiner asks about prophylactic fixation of impending pathological fractures in metastatic bone disease. Which of the following parameters is NOT part of the Mirels' scoring system?

. Site of the lesion
. Nature of the lesion (blastic, mixed, or lytic)
. Size of the lesion relative to bone diameter
. Primary tumor histology (e.g., breast, prostate, lung)
. Severity of pain

Correct Answer & Explanation

. Primary tumor histology (e.g., breast, prostate, lung)

Explanation

Mirels' criteria are used to predict the risk of pathological fracture and guide prophylactic fixation. The score relies on the site, size, nature (lytic/blastic), and pain level, but does not include the primary tumor's specific histological type.

Question 2342

Topic: 10. Pathology and Oncology

A 55-year-old male presents with a destructive lesion of the proximal femur. Biopsy reveals areas of low-grade hyaline cartilage directly adjacent to a high-grade pleomorphic spindle cell sarcoma with no osteoid formation. What is the most likely diagnosis?

. Clear cell chondrosarcoma
. Mesenchymal chondrosarcoma
. Dedifferentiated chondrosarcoma
. Chondroblastic osteosarcoma
. Secondary chondrosarcoma

Correct Answer & Explanation

. Dedifferentiated chondrosarcoma

Explanation

Dedifferentiated chondrosarcoma is characterized by a bimorphic histological appearance featuring a low-grade cartilaginous component abruptly transitioning into a high-grade, non-cartilaginous sarcoma (e.g., osteosarcoma, fibrosarcoma, or undifferentiated pleomorphic sarcoma). The abrupt transition and absence of osteoid in the high-grade spindle cell area differentiate it from chondroblastic osteosarcoma, which typically shows malignant osteoid production mixed with malignant cartilage. Dedifferentiated chondrosarcomas carry a very poor prognosis.

Question 2343

Topic: 10. Pathology and Oncology
A 16-year-old female with distal femoral osteosarcoma undergoes neoadjuvant chemotherapy followed by surgical resection. The pathology report notes a Huvos Grade III response. What percentage of tumor necrosis does this grade represent?
. Less than 50% necrosis
. 50% to 90% necrosis
. 90% to 99% necrosis
. 100% necrosis (no viable tumor cells)
. Increased tumor volume with no necrosis

Correct Answer & Explanation

. 90% to 99% necrosis

Explanation

The Huvos grading system assesses the histologic response of osteosarcoma to neoadjuvant chemotherapy, which is an important prognostic indicator. Grade I: Little to no response (<50% necrosis). Grade II: 50% to 90% necrosis. Grade III: 90% to 99% necrosis (predominant necrosis with scattered viable cells). Grade IV: 100% necrosis (no viable cells). A good response is typically defined as 90% or greater necrosis (Huvos Grades III and IV), which correlates with improved overall survival.

Question 2344

Topic: 10. Pathology and Oncology

A 35-year-old male presents with indolent pain in his lower leg. Radiographs reveal a multi-lobulated, lytic, eccentric lesion in the anterior tibial diaphysis. Biopsy reveals islands of epithelial cells in a fibrous stroma. Which of the following immunohistochemical markers is most likely positive?

. S-100
. Cytokeratin
. Vimentin only
. CD99
. Desmin

Correct Answer & Explanation

. Cytokeratin

Explanation

Adamantinoma is a low-grade malignant bone tumor that typically occurs in the anterior diaphysis of the tibia. It is characterized by biphasic histology (epithelial and osteofibrous components) and stains positive for epithelial markers such as cytokeratin, distinguishing it from osteofibrous dysplasia.

Question 2345

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a painful mass in his left thigh. Radiographs demonstrate an aggressive, permeative diaphyseal lesion in the femur with a prominent 'onion-skin' periosteal reaction. Core needle biopsy confirms the diagnosis of Ewing sarcoma. Which of the following chromosomal translocations is most characteristic of this tumor?

. t(11;22)(q24;q12)
. t(X;18)(p11;q11)
. t(12;16)(q13;p11)
. t(2;13)(q35;q14)
. t(9;22)(q34;q11)

Correct Answer & Explanation

. t(11;22)(q24;q12)

Explanation

Ewing sarcoma is characterized by the t(11;22)(q24;q12) translocation in approximately 85-90% of cases, leading to the fusion of the EWS gene on chromosome 22 with the FLI1 gene on chromosome 11. t(X;18) is seen in synovial sarcoma. t(12;16) is seen in myxoid liposarcoma. t(2;13) is seen in alveolar rhabdomyosarcoma.

Question 2346

Topic: 10. Pathology and Oncology

A 30-year-old male presents with a slowly enlarging, painless mass deep in the soft tissues near his knee joint. Biopsy reveals a biphasic tumor with both epithelial and spindle cell components. Molecular testing is ordered. Which of the following chromosomal translocations is diagnostic of this neoplasm?

. t(11;22)(q24;q12)
. t(X;18)(p11;q11)
. t(12;16)(q13;p11)
. t(2;13)(q35;q14)
. t(9;22)(q22;q12)

Correct Answer & Explanation

. t(X;18)(p11;q11)

Explanation

The patient has a synovial sarcoma, which characteristically demonstrates the t(X;18)(p11;q11) translocation, resulting in the SYT-SSX fusion gene. t(11;22) is seen in Ewing sarcoma; t(12;16) in myxoid liposarcoma; t(2;13) in alveolar rhabdomyosarcoma; and t(9;22) in extraskeletal myxoid chondrosarcoma.

Question 2347

Topic: 10. Pathology and Oncology
A 60-year-old man presents with a painful mass in his right pelvis. Biopsy reveals a primary conventional chondrosarcoma, grade II. What is the most appropriate definitive management for this patient?
. Neoadjuvant chemotherapy followed by wide surgical resection
. Wide surgical resection alone
. Intralesional curettage with local adjuvant therapy (e.g., phenol, argon beam)
. Definitive radiation therapy
. Wide surgical resection followed by adjuvant chemotherapy

Correct Answer & Explanation

. Wide surgical resection alone

Explanation

Conventional chondrosarcomas are generally poorly responsive to both chemotherapy and radiation therapy. The mainstay of treatment for intermediate to high-grade (Grade II or III) and pelvic chondrosarcomas is wide surgical resection with negative margins. Intralesional curettage is reserved only for benign or specific low-grade (Grade I) cartilaginous tumors in the appendicular skeleton.

Question 2348

Topic: 10. Pathology and Oncology

A 16-year-old male presents with severe knee pain after minor trauma. Radiographs show a purely lytic, expansile lesion in the distal femoral metaphysis. MRI demonstrates multiple fluid-fluid levels within the lesion. An incisional biopsy is performed to differentiate between an aneurysmal bone cyst (ABC) and a telangiectatic osteosarcoma. Which of the following histological findings definitively confirms a diagnosis of telangiectatic osteosarcoma?

. Presence of multinucleated giant cells
. Blood-filled cavernous spaces lacking an endothelial lining
. Reactive woven bone rimmed by prominent osteoblasts
. High-grade malignant stromal cells with nuclear atypia in the septa
. Abundant benign fibrous tissue with hemosiderin-laden macrophages

Correct Answer & Explanation

. High-grade malignant stromal cells with nuclear atypia in the septa

Explanation

Telangiectatic osteosarcoma mimics an aneurysmal bone cyst (ABC) both radiographically (lytic, expansile) and on MRI (fluid-fluid levels). Grossly, both appear as blood-filled, cystic spaces. The crucial differentiating factor is histological: while an ABC has benign septa containing fibroblasts, reactive woven bone, and multinucleated giant cells, a telangiectatic osteosarcoma is characterized by highly atypical, pleomorphic, and malignant sarcomatous cells with frequent mitoses located within the septations.

Question 2349

Topic: 10. Pathology and Oncology
A 55-year-old male is diagnosed with a massive conventional chondrosarcoma of the proximal femur. Staging shows no evidence of distant metastasis. The multidisciplinary tumor board recommends treatment. Which of the following constitutes the primary and most effective treatment modality for conventional intermediate to high-grade chondrosarcomas?
. Neoadjuvant chemotherapy followed by wide surgical excision
. Primary radiation therapy to the lesion
. Wide surgical excision alone
. Intralesional curettage with phenol adjuvant
. Radiofrequency ablation

Correct Answer & Explanation

. Wide surgical excision alone

Explanation

Conventional chondrosarcomas are characterized by abundant extracellular cartilage matrix, poor vascularity, and slow division rates, rendering them highly resistant to both chemotherapy and radiation therapy. Therefore, the mainstay of treatment for intermediate (Grade II) to high-grade (Grade III) conventional chondrosarcomas is wide surgical excision with negative margins. Intralesional curettage is only considered for benign cartilage lesions (enchondromas) or very select low-grade (Grade I/atypical cartilaginous tumors) in the appendicular skeleton.

Question 2350

Topic: 10. Pathology and Oncology

A 55-year-old male presents with deep thigh pain. Radiographs of the proximal femur demonstrate a large, lucent lesion with intralesional "ring and arc" calcifications and endosteal scalloping involving more than 2/3 of the cortical thickness. Core needle biopsy confirms atypical chondrocytes with abundant hypercellular stroma, consistent with an intermediate-grade (Grade 2) conventional chondrosarcoma. What is the most appropriate management?

. Extended intralesional curettage and bone grafting
. Wide surgical resection and reconstruction
. Neoadjuvant chemotherapy followed by wide resection
. Primary radiation therapy alone
. Radiofrequency ablation

Correct Answer & Explanation

. Wide surgical resection and reconstruction

Explanation

Conventional chondrosarcomas (Grades 2 and 3) are treated with wide surgical resection to achieve negative margins. They are notoriously resistant to both chemotherapy and radiation therapy. Extended curettage is only appropriate for benign cartilage tumors or select low-grade (Grade 1) atypical cartilaginous tumors in the appendicular skeleton.

Question 2351

Topic: 10. Pathology and Oncology

A 14-year-old male presents with chronic left knee pain. Radiographs show a well-defined, eccentric, lytic lesion localized entirely within the proximal tibial epiphysis, with a thin sclerotic margin. Biopsy reveals mononuclear cells with scattered multinucleated giant cells and areas of 'chicken-wire' calcification. What is the most likely diagnosis?

. Giant cell tumor
. Chondromyxoid fibroma
. Chondroblastoma
. Osteoblastoma
. Clear cell chondrosarcoma

Correct Answer & Explanation

. Chondroblastoma

Explanation

Chondroblastoma is a rare benign cartilage tumor that characteristically arises in the epiphysis or apophysis of long bones in skeletally immature patients (open physis). Histologically, it is defined by chondroblasts, osteoclast-like giant cells, and distinctive pericellular ('chicken-wire') calcifications.

Question 2352

Topic: Bone Tumors

A 19-year-old male presents with dull, aching back pain that is worse at night. Radiographs and CT demonstrate a 2.5 cm radiolucent lesion with a sclerotic margin in the posterior elements of L4. Biopsy shows woven bone trabeculae lined by prominent osteoblasts in a vascular connective tissue stroma. What is the most likely diagnosis?

. Osteoid osteoma
. Osteoblastoma
. Aneurysmal bone cyst
. Chondroblastoma
. Osteosarcoma

Correct Answer & Explanation

. Osteoblastoma

Explanation

Histologically, osteoid osteoma and osteoblastoma are nearly identical (woven bone, prominent osteoblasts, vascular stroma). The primary distinguishing factor is size: lesions greater than 1.5 to 2.0 cm are classified as osteoblastomas. Osteoblastomas also have a higher propensity for progressive growth and can cause neurologic symptoms when located in the spine.

Question 2353

Topic: 10. Pathology and Oncology
A 14-year-old boy is diagnosed with high-grade intramedullary osteosarcoma of the distal femur. He undergoes 10 weeks of neoadjuvant chemotherapy followed by wide surgical resection and endoprosthetic reconstruction. Which of the following is the most important independent prognostic factor for his overall survival?
. Tumor volume at initial presentation
. Histologic subtype of the diagnostic biopsy
. Percentage of tumor necrosis found in the resected specimen
. Patient age at the time of diagnosis
. Serum alkaline phosphatase level at presentation

Correct Answer & Explanation

. Percentage of tumor necrosis found in the resected specimen

Explanation

The histologic response to neoadjuvant chemotherapy, measured by the percentage of tumor necrosis in the resected specimen, is the most powerful and reliable predictor of disease-free and overall survival in patients with osteosarcoma. Greater than 90% necrosis (Huvos Grade III or IV) is considered a 'good response' and is associated with a significantly better prognosis.

Question 2354

Topic: 10. Pathology and Oncology

A 60-year-old male undergoes a core needle biopsy of a painless, slowly enlarging deep mass in his anterior thigh. Pathology returns as a high-grade pleomorphic sarcoma. Staging CT scans of the chest, abdomen, and pelvis are negative for metastasis. What is the most appropriate definitive management?

. Primary hip disarticulation
. Marginal excision followed by systemic chemotherapy
. Wide local excision and radiation therapy
. Preoperative chemotherapy, wide local excision, and postoperative chemotherapy
. Intralesional curettage and cementation

Correct Answer & Explanation

. Wide local excision and radiation therapy

Explanation

The standard of care for localized, high-grade soft tissue sarcomas of the extremity is limb-sparing wide local excision combined with radiation therapy (either pre- or post-operative) to maximize local control. Adjuvant chemotherapy has a controversial survival benefit in adult soft tissue sarcomas and is not routinely standardized without specific indications, making wide excision and radiation the correct fundamental choice.

Question 2355

Topic: 10. Pathology and Oncology

A 14-year-old boy is diagnosed with conventional high-grade osteosarcoma of the distal femur. After staging, which of the following factors represents the single most significant predictor of overall survival?

. Size of the primary tumor
. Patient age at diagnosis
. Histologic subtype (e.g., osteoblastic vs. chondroblastic)
. Presence of distant metastasis at presentation
. Serum alkaline phosphatase level

Correct Answer & Explanation

. Presence of distant metastasis at presentation

Explanation

While factors such as tumor volume, histologic response to neoadjuvant chemotherapy (percentage of tumor necrosis), and elevated alkaline phosphatase all provide prognostic information, the presence of clinically detectable distant metastasis (most commonly to the lungs) at the time of presentation is the single most important and devastating prognostic factor, drastically reducing the 5-year survival rate.

Question 2356

Topic: 10. Pathology and Oncology

A 28-year-old male presents with a slowly enlarging, painful mass near his knee joint. Radiographs reveal a soft tissue mass with stippled calcifications. Biopsy demonstrates a biphasic pattern of epithelial and spindle cells. Which specific chromosomal translocation is characteristic of this tumor?

. t(11;22)
. t(X;18)
. t(9;22)
. t(2;13)
. t(12;16)

Correct Answer & Explanation

. t(X;18)

Explanation

Synovial sarcoma classically presents as a slow-growing soft tissue mass near a joint (often the knee) with calcifications visible on X-ray in up to 30% of cases. The pathognomonic chromosomal translocation is t(X;18)(p11;q11), which fuses the SYT gene on chromosome 18 with SSX1, SSX2, or SSX4 on the X chromosome.

Question 2357

Topic: 10. Pathology and Oncology

A 65-year-old male presents with deep sacral pain and recent-onset bowel/bladder dysfunction. MRI demonstrates a destructive midline mass arising from the sacrum. Biopsy reveals large cells with prominent intracytoplasmic vacuoles (physaliferous cells) in a myxoid background. What is the most appropriate definitive management for this lesion?

. Chemotherapy followed by radiation
. Curettage and cementation
. En bloc wide surgical resection
. Definitive stereotactic radiosurgery
. Observation with serial MRI

Correct Answer & Explanation

. En bloc wide surgical resection

Explanation

The clinical presentation and histopathological findings (midline sacral mass, physaliferous cells) are pathognomonic for chordoma. Chordomas are slow-growing but locally aggressive and are notoriously radioresistant and chemoresistant. The treatment of choice for sacral chordoma is en bloc wide surgical resection to achieve negative margins, which offers the best chance for local control and long-term survival.

Question 2358

Topic: Bone Tumors
A 70-year-old female presents with insidious onset of back pain and anemia. Radiographs demonstrate 'punched-out' lytic lesions in the skull and a compression fracture of T12. Laboratory tests show a monoclonal spike on serum protein electrophoresis. Which of the following is currently the most sensitive whole-body imaging modality for detecting skeletal involvement in this disease?
. Technetium-99m bone scan
. Whole-body low-dose CT
. Standard radiographic skeletal survey
. Diagnostic ultrasound
. Gallium scan

Correct Answer & Explanation

. Whole-body low-dose CT

Explanation

The diagnosis is multiple myeloma. The classic Technetium-99m bone scan depends on osteoblastic activity and is often falsely negative ('cold') in multiple myeloma because the lesions are purely osteolytic with minimal reactive bone formation. Whole-body low-dose CT (WBLDCT) or whole-body MRI are now the most sensitive imaging modalities and have largely replaced standard skeletal surveys for detecting skeletal lesions in multiple myeloma.

Question 2359

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with thigh pain and a low-grade fever. Radiographs show a permeative diaphyseal lesion of the femur with a 'periosteal onion-skin' reaction. A biopsy confirms sheets of small round blue cells. Which of the following genetic translocations is most characteristic of this patient's diagnosis?

. t(11;22) (q24;q12)
. t(9;22) (q34;q11)
. t(2;13) (q35;q14)
. t(12;16) (q13;p11)
. t(X;18) (p11;q11)

Correct Answer & Explanation

. t(11;22) (q24;q12)

Explanation

The clinical presentation and biopsy are classic for Ewing sarcoma. The most common chromosomal translocation associated with Ewing sarcoma is t(11;22) (q24;q12), which results in the EWSR1-FLI1 fusion protein. Option B is for CML (Philadelphia chromosome). Option C is alveolar rhabdomyosarcoma. Option D is myxoid liposarcoma. Option E is synovial sarcoma.

Question 2360

Topic: 10. Pathology and Oncology
A 15-year-old girl diagnosed with osteosarcoma of the distal femur completes a course of neoadjuvant chemotherapy, followed by wide surgical resection. Pathological analysis of the resected tumor specimen reveals 95% tumor necrosis. In the context of osteosarcoma management, what does this specific pathological finding indicate?
. It requires an immediate change to a completely different adjuvant chemotherapy regimen
. It is an indication that radiation therapy is necessary to achieve local control
. It signifies a good biological response to chemotherapy and is a strong predictor of improved overall survival
. It suggests that surgical margins are likely positive and re-excision is required
. It is a poor prognostic factor indicating an aggressive, rapidly necrotic tumor phenotype

Correct Answer & Explanation

. It signifies a good biological response to chemotherapy and is a strong predictor of improved overall survival

Explanation

The degree of tumor necrosis after neoadjuvant chemotherapy is one of the most important prognostic factors in osteosarcoma. A histological response of 90% or greater tumor necrosis (often referred to as a 'good response' or Huvos grade III/IV) is highly predictive of better long-term overall survival and progression-free survival. Patients with <90% necrosis have a poorer prognosis.

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