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10. Pathology and Oncology MCQs

Practice Set 200 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 3981

Topic: 10. Pathology and Oncology

A 40-year-old male presents with persistent knee pain. Radiographs show a lytic lesion in the distal femur without matrix calcification or periosteal reaction. Biopsy reveals uniform spindle cells without significant atypia or mitotic activity. CD34 immunohistochemistry is positive. What is the most likely diagnosis?

. Osteosarcoma
. Chondrosarcoma
. Fibrosarcoma (low-grade)
. Solitary fibrous tumor of bone
. Ewing Sarcoma

Correct Answer & Explanation

. Solitary fibrous tumor of bone

Explanation

The clinical scenario (lytic lesion, no matrix calcification/periosteal reaction), histological description (uniform spindle cells, no significant atypia or mitotic activity), and especially the positive CD34 immunohistochemistry are highly characteristic of a Solitary Fibrous Tumor (SFT) of bone. SFTs are typically CD34 positive. Fibrosarcomas, especially low-grade, can be spindle cell but usually have more atypia and often lack strong CD34 positivity. Osteosarcoma and chondrosarcoma have distinct matrix formation. Ewing sarcoma is a small round blue cell tumor. This is a challenging question requiring knowledge of specific immunohistochemical markers for less common bone tumors.

Question 3982

Topic: 10. Pathology and Oncology

Which of the following interventions has significantly improved the survival rates for patients with high-grade osteosarcoma over the past few decades?

. Routine amputation for all extremity lesions.
. Introduction of advanced pain management protocols.
. Development of sophisticated limb salvage techniques.
. Adoption of multimodal therapy including neoadjuvant and adjuvant chemotherapy.
. Widespread use of proton beam radiation therapy.

Correct Answer & Explanation

. Adoption of multimodal therapy including neoadjuvant and adjuvant chemotherapy.

Explanation

The most significant improvement in survival rates for high-grade osteosarcoma came with the adoption of multimodal therapy, specifically the integration of effective systemic chemotherapy (neoadjuvant and adjuvant) with aggressive surgical resection. Prior to chemotherapy, survival rates were poor. Chemotherapy targets micrometastatic disease and improves local control when combined with surgery. While limb salvage techniques and pain management have improved quality of life, and radiation can play a role, it is the systemic chemotherapy that fundamentally changed the survival prognosis for this highly metastatic tumor.

Question 3983

Topic: 10. Pathology and Oncology

A 50-year-old female presents with a slowly enlarging, deep-seated mass in her posterior thigh. Biopsy reveals a well-differentiated liposarcoma. What is the primary concern for this specific subtype of liposarcoma, despite its 'well-differentiated' nature?

. High risk of distant metastasis.
. High rate of malignant transformation to a higher-grade sarcoma (dedifferentiation).
. Extreme sensitivity to radiation therapy.
. Frequent involvement of regional lymph nodes.
. Rapid growth leading to early neurovascular compromise.

Correct Answer & Explanation

. High rate of malignant transformation to a higher-grade sarcoma (dedifferentiation).

Explanation

Well-differentiated liposarcoma (WDLPS), especially in retroperitoneal or deep extremity locations, has a primary concern of local recurrence and a significant risk of dedifferentiation into a higher-grade, more aggressive non-lipogenic sarcoma (dedifferentiated liposarcoma). This dedifferentiation markedly worsens the prognosis and increases metastatic potential. While WDLPS rarely metastasizes as WDLPS, the dedifferentiated component carries metastatic risk. It is not highly sensitive to radiation, does not frequently involve lymph nodes, and typically has a slow growth rate, unlike high-grade sarcomas.

Question 3984

Topic: 10. Pathology and Oncology

What is the most common primary malignant bone tumor in adults, typically presenting as multifocal lytic lesions, often with a characteristic 'punched-out' appearance on X-ray?

. Osteosarcoma
. Chondrosarcoma
. Ewing sarcoma
. Multiple myeloma
. Fibrosarcoma

Correct Answer & Explanation

. Multiple myeloma

Explanation

Multiple myeloma is the most common primary malignant tumor of bone in adults. It is a plasma cell malignancy that typically presents as multifocal lytic bone lesions, often described as 'punched-out' lesions without sclerotic margins on radiographs. Osteosarcoma, chondrosarcoma, and Ewing sarcoma are more common in younger age groups (except secondary chondrosarcoma and some osteosarcomas). Fibrosarcoma is rare.

Question 3985

Topic: 10. Pathology and Oncology

Which of the following immunohistochemical markers is typically used to confirm the diagnosis of Ewing sarcoma?

. S-100
. Desmin
. CD31
. CD99 (MIC2)
. MyoD1

Correct Answer & Explanation

. CD99 (MIC2)

Explanation

Ewing sarcoma is characterized by a specific chromosomal translocation, most commonly t(11;22), which leads to the EWS-FLI1 fusion protein. Immunohistochemically, Ewing sarcoma cells typically show strong, diffuse membrane positivity for CD99 (MIC2 protein). S-100 is for neural/cartilaginous tumors, Desmin for muscle differentiation, CD31 for vascular tumors, and MyoD1 for rhabdomyosarcoma. CD99 is a key diagnostic marker for Ewing sarcoma.

Question 3986

Topic: 10. Pathology and Oncology

A 10-year-old patient with an osteosarcoma of the proximal tibia is undergoing limb salvage surgery. During resection, the surgeon notices that the posterior cortex of the tibia is involved, and the tumor is very close to the popliteal artery. What kind of reconstruction would be most appropriate in this scenario if a vascular graft is required?

. Allograft reconstruction.
. Endoprosthetic replacement.
. Rotationplasty.
. Arthrodesis.
. Vascular graft alone without bone reconstruction.

Correct Answer & Explanation

. Rotationplasty.

Explanation

If the popliteal artery is involved and requires resection and vascular grafting, especially in a growing child with osteosarcoma of the proximal tibia, a rotationplasty (e.g., Van Nes rotationplasty) is often an excellent reconstructive option. Rotationplasty involves resecting the tumor, rotating the distal limb (foot and ankle) 180 degrees, and reattaching it to the proximal femur. The ankle then functions as a knee joint for a prosthetic limb, providing a highly functional and durable option, especially when complex vascular or nerve resections are necessary and other limb salvage options might lead to a non-functional limb or complex growth issues. Allograft and endoprosthetics are less ideal with major vascular reconstruction needs in this context, and arthrodesis is a fusion, not optimal in a growing child with vascular compromise.

Question 3987

Topic: 10. Pathology and Oncology

What is the standard approach to biopsy for a suspected musculoskeletal sarcoma?

. Incisional biopsy, typically performed by a general surgeon.
. Excisional biopsy for lesions smaller than 3 cm.
. Fine needle aspiration (FNA) for definitive diagnosis.
. Core needle biopsy, performed by an orthopedic oncologist or interventional radiologist, following an MRI-guided approach.
. Open biopsy, performed by any surgeon, ensuring the incision is placed transversely.

Correct Answer & Explanation

. Core needle biopsy, performed by an orthopedic oncologist or interventional radiologist, following an MRI-guided approach.

Explanation

The standard and most recommended approach for biopsy of a suspected musculoskeletal sarcoma is a core needle biopsy, performed by an orthopedic oncologist or an experienced interventional radiologist. The biopsy should ideally be guided by imaging (usually MRI) to ensure accurate sampling of the tumor and to plan the trajectory carefully. The biopsy tract must be placed in a way that it can be completely excised with the definitive resection specimen to avoid tumor contamination of surrounding tissues. FNA is often insufficient for definitive diagnosis and grading. Incisional and excisional biopsies are surgical but carry higher morbidity and risk of contamination if not planned carefully by an orthopedic oncologist, and excisional biopsy for 'small lesions' is generally discouraged without prior diagnosis due to the risk of an inadequate oncologic margin if it turns out to be malignant. Open biopsy by 'any surgeon' with a 'transverse incision' (which cannot be easily excised longitudinally) is absolutely contraindicated due to high risk of contaminating multiple compartments and making definitive limb salvage much more difficult or impossible.

Question 3988

Topic: 10. Pathology and Oncology

Which of the following primary bone tumors most commonly metastasizes to other bones, in addition to the lungs?

. Osteosarcoma
. Chondrosarcoma
. Giant Cell Tumor of Bone
. Ewing sarcoma
. Fibrosarcoma of bone

Correct Answer & Explanation

. Ewing sarcoma

Explanation

Ewing sarcoma has a high propensity for systemic spread, and its most common sites of metastasis are the lungs and other bones (skeletal metastases), including bone marrow. While osteosarcoma also metastasizes to the lungs and can less commonly involve other bones, Ewing sarcoma is particularly known for its predilection for bone-to-bone metastasis. Chondrosarcoma primarily metastasizes to the lungs. GCTB rarely metastasizes, usually to the lungs. Fibrosarcoma of bone is rare and also primarily to the lungs.

Question 3989

Topic: 10. Pathology and Oncology
A patient is diagnosed with a high-grade pleomorphic undifferentiated sarcoma (PUS) of the proximal humerus. During staging, a small, indeterminate pulmonary nodule is identified. The primary tumor is large and has invaded the deltoid muscle. Which of the following best describes the overall stage and a potential management dilemma related to this nodule?
. Stage IIB; the nodule is likely benign, proceed with surgery first.
. Stage III; the nodule upstages the patient, but its nature (M1a vs. benign) requires careful re-evaluation after initial systemic therapy.
. Stage IVA; the nodule immediately qualifies as distant metastasis, proceed with palliative care.
. Stage IB; the high grade is offset by the small nodule size.
. Stage IVB; the deltoid invasion is the key factor determining stage.

Correct Answer & Explanation

. Stage III; the nodule upstages the patient, but its nature (M1a vs. benign) requires careful re-evaluation after initial systemic therapy.

Explanation

This is a challenging scenario often encountered. The high-grade PUS and deltoid invasion suggest an aggressive primary. A small, indeterminate pulmonary nodule, especially if not clearly M1 (e.g., if it's too small or lacks aggressive features), presents a dilemma. If definitively M1, it would be Stage IVA for soft tissue sarcoma (N0M1). However, small indeterminate nodules (especially in the context of high-grade sarcoma where prompt systemic therapy is indicated) are often managed by proceeding with neoadjuvant chemotherapy first, then re-evaluating the nodule. If it grows, it's M1; if it disappears or remains stable, it's likely benign. Therefore, the nodule itself upstages the patient if it is indeed metastatic, making it at least Stage III (if N1M0, but here M0/M1 is the question) or Stage IVA (if M1). The insight here is the nuanced approach to indeterminate lesions: don't automatically assume M1 without strong evidence, especially when it fundamentally changes the treatment paradigm, and use the initial systemic therapy phase for re-evaluation.

Question 3990

Topic: 10. Pathology and Oncology

A 3-year-old child presents with a limp, and radiographs show an osteochondroma arising from the distal femur, close to the physis. Which of the following is the most concerning potential complication in the long term?

. Pathologic fracture through the lesion
. Development of a malignant transformation (chondrosarcoma)
. Progressive limb length discrepancy
. Impingement on neurovascular structures
. Joint stiffness due to capsular irritation

Correct Answer & Explanation

. Progressive limb length discrepancy

Explanation

While all listed are potential complications of osteochondromas, for a lesion near the physis in a growing child, progressive limb length discrepancy or angular deformity is a significant long-term concern. The osteochondroma can tether the growth plate, leading to asymmetric growth. Malignant transformation to chondrosarcoma is rare in solitary osteochondromas (<1%) but higher in hereditary multiple exostoses (5-25%). Neurovascular impingement and joint stiffness are less common but possible. Pathologic fracture is also possible but less frequent than growth disturbance in this age group and location.

Question 3991

Topic: 10. Pathology and Oncology

Which of the following is the most common benign bone tumor?

. Osteochondroma
. Enchondroma
. Non-ossifying fibroma
. Osteoid osteoma
. Fibrous dysplasia

Correct Answer & Explanation

. Osteochondroma

Explanation

Osteochondroma is widely considered the most common benign bone tumor, accounting for 35-50% of all benign bone tumors. It is characterized by an exophytic growth covered by a cartilaginous cap, arising from the surface of bones near growth plates. While enchondromas, non-ossifying fibromas (NOF), and osteoid osteomas are also common benign bone tumors, osteochondroma holds the top spot. Fibrous dysplasia is a developmental anomaly, not strictly a tumor.

Question 3992

Topic: 10. Pathology and Oncology

Which of the following statements regarding osteosarcoma is FALSE?

. It is the most common primary malignant bone tumor in children and adolescents.
. It typically presents with pain and swelling, often near a joint.
. Metastatic disease at presentation, most commonly to the lungs, is rare.
. Chemotherapy is an essential component of treatment.
. Radiographs often show a 'sunburst' appearance or Codman's triangle.

Correct Answer & Explanation

. Metastatic disease at presentation, most commonly to the lungs, is rare.

Explanation

Metastatic disease at presentation, most commonly to the lungs, isnot rare; it occurs in approximately 15-20% of patients with osteosarcoma, which significantly impacts prognosis. Early detection of lung metastases is crucial for treatment planning. All other statements are true: osteosarcoma is the most common primary malignant bone tumor in children and adolescents, presents with pain/swelling, requires neoadjuvant and adjuvant chemotherapy, and can have classic radiographic findings like the sunburst appearance (periosteal reaction) or Codman's triangle.

Question 3993

Topic: 10. Pathology and Oncology

Which of the following statements about Paget's disease of bone is FALSE?

. It is characterized by disorganized bone remodeling.
. It commonly affects the skull, spine, pelvis, and long bones.
. Elevated serum alkaline phosphatase is a common biochemical marker.
. Bisphosphonates are the first-line medical treatment.
. Malignant transformation to osteosarcoma is a common complication.

Correct Answer & Explanation

. Malignant transformation to osteosarcoma is a common complication.

Explanation

Malignant transformation of Paget's disease to osteosarcoma (or other sarcomas) is ararecomplication, occurring in less than 1% of patients. While it is a serious potential complication, it is not common. All other statements are true: Paget's disease (osteitis deformans) involves accelerated, disorganized bone remodeling, often affecting the axial skeleton and long bones. Elevated alkaline phosphatase reflects high bone turnover. Bisphosphonates are the mainstay of medical treatment to normalize bone turnover and reduce symptoms.

Question 3994

Topic: 10. Pathology and Oncology

Which of the following factors most strongly predicts a poor prognosis in patients with metastatic bone disease from solid tumors?

. Pathologic fracture requiring surgical stabilization.
. Hypercalcemia.
. Visceral metastases.
. Age over 70 years.
. Primary tumor type (e.g., breast vs. prostate).

Correct Answer & Explanation

. Visceral metastases.

Explanation

Visceral metastases (e.g., to the lung, liver, brain) are the strongest predictors of a poor prognosis and shorter survival in patients with metastatic bone disease. While pathologic fractures and hypercalcemia are significant complications indicating extensive disease, the presence of visceral metastases implies a more aggressive, widespread disease burden. Age can be a factor but is less influential than the extent of systemic disease. Primary tumor type influences prognosis, but visceral spread is often the key determinant of life expectancy.

Question 3995

Topic: 10. Pathology and Oncology

Which of the following is the most important factor dictating the prognosis and management of osteosarcoma?

. Patient age
. Tumor size
. Location of the primary tumor
. Presence of metastatic disease at presentation
. Histologic subtype

Correct Answer & Explanation

. Presence of metastatic disease at presentation

Explanation

The presence of metastatic disease at presentation is by far the most important prognostic factor in osteosarcoma. Patients with metastatic disease (most commonly to the lungs) have a significantly worse prognosis than those with localized disease. While tumor size, location, patient age, and histologic subtype can influence prognosis, they are secondary to the presence or absence of metastases.

Question 3996

Topic: 10. Pathology and Oncology

What is the most common primary malignant bone tumor in adults?

. Osteosarcoma
. Ewing sarcoma
. Chondrosarcoma
. Multiple myeloma
. Fibrosarcoma

Correct Answer & Explanation

. Multiple myeloma

Explanation

Multiple myeloma is the most common primary malignant bone tumor in adults. While often considered a hematologic malignancy, it manifests primarily as bone lesions. Osteosarcoma and Ewing sarcoma are more common in children and adolescents. Chondrosarcoma is the second most common primary bone sarcoma in adults, but less common than multiple myeloma. Fibrosarcoma is a rare soft tissue sarcoma that can involve bone secondarily.

Question 3997

Topic: 10. Pathology and Oncology

A 12-year-old boy presents with a painful mass in his distal femur. Biopsy reveals osteosarcoma. Which of the following statements regarding the management of osteosarcoma is true?

. Chemotherapy is not typically used for localized disease.
. Limb salvage surgery is universally preferred over amputation.
. The primary goal of surgery is complete tumor resection with adequate margins.
. Radiation therapy is the primary treatment for unresectable tumors.
. Monitoring for recurrence typically involves regular bone scans only.

Correct Answer & Explanation

. The primary goal of surgery is complete tumor resection with adequate margins.

Explanation

The primary goal of surgery for osteosarcoma, whether limb salvage or amputation, is complete tumor resection with adequate oncologic margins to prevent local recurrence. Chemotherapy (neoadjuvant and adjuvant) is a cornerstone of treatment for virtually all localized osteosarcomas. While limb salvage is often attempted, it depends on tumor characteristics and patient factors, and amputation remains a viable and sometimes necessary option. Radiation therapy has a limited role in osteosarcoma due to its radioresistance, typically reserved for unresectable tumors or palliative care. Monitoring involves chest CT for lung metastases and often bone scans, but not bone scans only.

Question 3998

Topic: 10. Pathology and Oncology

What is the most common type of soft tissue sarcoma in adults?

. Liposarcoma
. Synovial sarcoma
. Leiomyosarcoma
. Undifferentiated pleomorphic sarcoma (UPS)
. Rhabdomyosarcoma

Correct Answer & Explanation

. Undifferentiated pleomorphic sarcoma (UPS)

Explanation

Undifferentiated pleomorphic sarcoma (UPS), formerly known as malignant fibrous histiocytoma (MFH), is considered the most common type of soft tissue sarcoma in adults. Liposarcoma is also very common, often cited as the second most common, but UPS usually takes the top spot overall. Synovial sarcoma and leiomyosarcoma are less common. Rhabdomyosarcoma is primarily a sarcoma of childhood.

Question 3999

Topic: 10. Pathology and Oncology

A 15-year-old boy presents with a permeative diaphyseal lesion in the femur demonstrating an 'onion skin' periosteal reaction. Which chromosomal translocation is most characteristically associated with this pathology?

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

Correct Answer & Explanation

. t(11;22)

Explanation

The clinical and radiographic presentation is classic for Ewing sarcoma. The hallmark genetic abnormality in Ewing sarcoma is the t(11;22)(q24;q12) chromosomal translocation, which results in the EWS-FLI1 fusion protein.

Question 4000

Topic: 10. Pathology and Oncology

A 12-year-old boy presents with an aggressive diaphyseal lesion of the femur featuring a 'periosteal onion-skin' reaction. A biopsy is performed. Molecular cytogenetic analysis of the tumor tissue is most likely to reveal which of the following chromosomal translocations?

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

Correct Answer & Explanation

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

Explanation

The clinical and radiographic presentation is classic for Ewing Sarcoma. Ewing Sarcoma is characterized by the t(11;22)(q24;q12) translocation in about 85-90% of cases, which results in the EWS-FLI1 fusion gene. t(X;18) is associated with Synovial Sarcoma; t(12;16) with Myxoid Liposarcoma; and t(2;13) with Alveolar Rhabdomyosarcoma.

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