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10. Pathology and Oncology MCQs

Practice Set 272 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 5421

Topic: 10. Pathology and Oncology

What is the primary concern when performing a biopsy through a previously contaminated field, such as an old surgical incision or an area of previous trauma?

. Increased risk of infection.
. Difficulty with wound healing.
. Potential for false-negative biopsy results.
. Disruption of oncologic planes and spread of tumor cells into an already compromised area.
. Increased blood loss.

Correct Answer & Explanation

. Disruption of oncologic planes and spread of tumor cells into an already compromised area.

Explanation

The primary concern when performing a biopsy through a previously contaminated field is the disruption of oncologic planes and the potential for spreading tumor cells into an already compromised or surgically altered area. This can make future wide en bloc resection more challenging and increase the risk of local recurrence. While infection risk, wound healing, and false-negatives are all possibilities, the impact on definitive tumor control is paramount in oncology.

Question 5422

Topic: 10. Pathology and Oncology

A biopsy for a suspected primary bone tumor is being performed. Which of the following is a crucial step for the surgical team to ensure the pathologist receives an optimal specimen?

. Rinsing the specimen with sterile water to remove blood.
. Placing the specimen in a dry sterile container for transport.
. Immediately placing the specimen in formalin solution.
. Ensuring the specimen is kept fresh/unfixed for potential molecular studies or specific cultures, and also fix a portion in formalin.
. Dividing the specimen into the smallest possible fragments.

Correct Answer & Explanation

. Ensuring the specimen is kept fresh/unfixed for potential molecular studies or specific cultures, and also fix a portion in formalin.

Explanation

For a suspected primary bone tumor, an optimal specimen often requires multiple processing methods. Part of the specimen should be kept fresh (unfixed) for potential molecular studies (e.g., FISH, RT-PCR for translocations), cytogenetics, or microbiological cultures if infection is in the differential. Another portion should be immediately placed in formalin for routine histopathology. Rinsing with water or placing in saline can cause cell lysis and damage. Placing all specimens in formalin prevents fresh tissue analysis. Dividing into small fragments is not always beneficial and can impede architectural assessment.

Question 5423

Topic: 10. Pathology and Oncology

When planning a biopsy for a suspected malignant lesion in the distal femur, which approach would be considered the LEAST desirable due to the risk of tumor dissemination and compromised future resection?

. Anterior approach through the vastus intermedius.
. Lateral approach through the vastus lateralis.
. Medial approach through the vastus medialis.
. Posterior approach violating multiple muscle compartments to reach a centrally located lesion.
. Anteromedial approach avoiding the neurovascular bundle.

Correct Answer & Explanation

. Posterior approach violating multiple muscle compartments to reach a centrally located lesion.

Explanation

A posterior approach to the distal femur, especially one that violates multiple muscle compartments to reach a centrally located lesion, is the least desirable. This approach contaminates multiple fascial planes and can spread tumor cells widely, making definitive en bloc resection of the contaminated tissue extremely difficult and significantly compromising limb-salvage surgery. All other approaches, if planned carefully (longitudinal, single compartment), are generally acceptable for distal femur lesions.

Question 5424

Topic: 10. Pathology and Oncology

A biopsy report indicates 'numerous plasma cells consistent with plasma cell dyscrasia'. What additional diagnostic procedure is typically crucial for full staging and management?

. PET-CT scan
. Serum protein electrophoresis (SPEP) and immunofixation
. Bone marrow biopsy from a separate site
. 24-hour urine for Bence-Jones protein
. All of the above

Correct Answer & Explanation

. All of the above

Explanation

A biopsy indicating plasma cell dyscrasia (e.g., solitary plasmacytoma or multiple myeloma) requires a comprehensive workup. This includes: serum protein electrophoresis (SPEP) and immunofixation to detect and quantify monoclonal proteins; 24-hour urine for Bence-Jones protein; a bone marrow biopsy from an uninvolved site to assess for systemic myeloma; and PET-CT scan for full body staging and to identify other myelomatous lesions. Therefore, all the listed options are crucial for complete diagnosis and staging.

Question 5425

Topic: 10. Pathology and Oncology

What is the primary indication for an excisional biopsy in the context of musculoskeletal tumor diagnosis?

. Large, aggressive high-grade sarcomas.
. Deep-seated lesions requiring extensive dissection.
. Superficial, small, well-circumscribed lesions highly suspected to be benign or low-grade malignant.
. Lesions with impending pathological fracture.
. Vertebral body lesions with neurological compromise.

Correct Answer & Explanation

. Superficial, small, well-circumscribed lesions highly suspected to be benign or low-grade malignant.

Explanation

Excisional biopsy is generally indicated for superficial, small, well-circumscribed lesions that are highly suspected to be benign (e.g., lipoma, epidermal inclusion cyst) or very low-grade malignant (e.g., dermatofibrosarcoma protuberans) where the entire lesion can be removed with a narrow, yet oncologically sound, margin without compromising subsequent definitive surgery. For large, aggressive, or deep-seated lesions, an incisional or core needle biopsy is preferred to obtain a diagnosis before planning definitive wide resection.

Question 5426

Topic: 10. Pathology and Oncology

The MOST common pitfall leading to a non-diagnostic or misleading biopsy in bone tumors is:

. Inadequate fixation of the specimen.
. Lack of radiologist expertise in image guidance.
. Sampling only necrotic or reactive areas of the tumor.
. Contamination of the specimen with normal bone marrow.
. Pathologist unfamiliarity with bone tumor pathology.

Correct Answer & Explanation

. Sampling only necrotic or reactive areas of the tumor.

Explanation

Sampling only necrotic, hemorrhagic, or reactive areas of the tumor (sampling error) is by far the most common pitfall leading to a non-diagnostic or misleading biopsy. Tumors are often heterogeneous, and a small core needle biopsy might miss the viable, diagnostic portions. While other factors listed can contribute, sampling error is the predominant issue, even for experienced operators.

Question 5427

Topic: 10. Pathology and Oncology

Prior to performing a biopsy of a suspected vascular bone tumor (e.g., metastatic renal cell carcinoma), which adjunctive procedure is often recommended to minimize blood loss?

. Pre-operative antibiotic prophylaxis.
. Pre-operative arterial embolization.
. Intra-operative cell saver use.
. Tourniquet application during biopsy.
. Administration of tranexamic acid.

Correct Answer & Explanation

. Pre-operative arterial embolization.

Explanation

For suspected vascular bone tumors (e.g., metastatic renal cell carcinoma, thyroid carcinoma, hemangioendothelioma), pre-operative arterial embolization of the feeding vessels is often recommended. This procedure can significantly reduce intra-operative blood loss during biopsy and subsequent definitive surgery. Tourniquet application is only feasible for distal extremity lesions. While cell saver and tranexamic acid can help manage blood loss, embolization directly addresses the hypervascularity of the lesion.

Question 5428

Topic: 10. Pathology and Oncology

What is the primary reason for avoiding multiple skin incisions for a single lesion biopsy in musculoskeletal oncology?

. To reduce post-operative pain.
. To minimize scarring.
. To decrease the risk of infection.
. To prevent widespread contamination of tissue planes, complicating definitive resection.
. To shorten the operative time.

Correct Answer & Explanation

. To prevent widespread contamination of tissue planes, complicating definitive resection.

Explanation

The primary reason for avoiding multiple skin incisions for a single lesion biopsy is to prevent widespread contamination of tissue planes. Each incision creates a new biopsy tract that must be excised during definitive surgery. Multiple tracts make it significantly more challenging to achieve a clean oncologic resection, potentially leading to local recurrence. Therefore, a single, carefully placed incision is crucial for limb-salvage surgery.

Question 5429

Topic: 10. Pathology and Oncology

A biopsy of a lesion in the proximal tibia reveals cartilaginous tissue consistent with an enchondroma. However, the patient's age (60 years) and the lesion's location (proximal tibia, often a site for chondrosarcoma) raise suspicion. What is the MOST appropriate next step?

. Treat as enchondroma and observe.
. Recommend immediate chemotherapy.
. Obtain a second opinion on the pathology slides and review imaging (MRI) carefully for signs of aggressiveness, possibly repeating biopsy if discordance persists.
. Perform a wide surgical resection without further biopsy.
. Initiate radiation therapy.

Correct Answer & Explanation

. Obtain a second opinion on the pathology slides and review imaging (MRI) carefully for signs of aggressiveness, possibly repeating biopsy if discordance persists.

Explanation

In this scenario, a chondroid lesion diagnosed as enchondroma in a 60-year-old in the proximal tibia (a common site for central chondrosarcoma) presents a classic clinicopathologic discordance. Low-grade chondrosarcomas can be very difficult to distinguish from enchondromas on small biopsies. The most appropriate step is to obtain a second opinion from an expert musculoskeletal pathologist, meticulously review the MRI for any signs of cortical destruction, soft tissue mass, or aggressive features, and if suspicion remains high, consider repeating the biopsy, possibly as an open incisional biopsy, to get a more representative sample. Treating as a benign enchondroma or proceeding to wide resection/chemotherapy without clear diagnosis would be inappropriate.

Question 5430

Topic: 10. Pathology and Oncology
Which of the following conditions is an absolute contraindication for a percutaneous core needle biopsy?
. Patient on anticoagulation therapy.
. Suspected osteoid osteoma.
. Inability to achieve adequate analgesia with local anesthetic.
. Lack of a safe biopsy corridor (e.g., adjacent to major neurovascular structures or vital organs).
. Patient refusal of general anesthesia.

Correct Answer & Explanation

. Lack of a safe biopsy corridor (e.g., adjacent to major neurovascular structures or vital organs).

Explanation

The most absolute contraindication for a percutaneous core needle biopsy is the lack of a safe biopsy corridor. If the needle trajectory would inevitably traverse major neurovascular structures, vital organs (e.g., lung, bowel, kidney, spinal cord), or highly vascular structures without embolization, the risks outweigh the benefits, and an open biopsy, or a different approach, might be necessary. While anticoagulation, pain, and refusal of general anesthesia pose challenges, they are relative contraindications that can often be managed.

Question 5431

Topic: 10. Pathology and Oncology

A biopsy is planned for a suspected bone lesion in a patient with a known bleeding disorder. Which of the following is the MOST appropriate strategy to minimize risk?

. Perform the biopsy with the smallest possible needle.
. Administer systemic corticosteroids prior to biopsy.
. Pre-biopsy correction of coagulopathy with appropriate factor replacement or reversal agents.
. Perform a blind biopsy without image guidance.
. Only perform an FNA to minimize trauma.

Correct Answer & Explanation

. Pre-biopsy correction of coagulopathy with appropriate factor replacement or reversal agents.

Explanation

For patients with bleeding disorders, pre-biopsy correction of coagulopathy with appropriate factor replacement, platelet transfusions, or reversal agents is the most crucial step to minimize the risk of hemorrhage. While using a small needle and FNA can reduce trauma, they may not provide adequate diagnostic material. Systemic corticosteroids are not indicated for bleeding disorders, and a blind biopsy is never preferred due to safety and accuracy concerns.

Question 5432

Topic: 10. Pathology and Oncology

The primary disadvantage of Fine Needle Aspiration (FNA) biopsy for diagnosing primary bone sarcomas compared to core needle biopsy is:

. Higher risk of infection.
. Greater patient discomfort.
. Inability to distinguish between benign and malignant lesions.
. Lack of architectural information, making grading and subtyping difficult.
. Prolonged healing time for the biopsy site.

Correct Answer & Explanation

. Lack of architectural information, making grading and subtyping difficult.

Explanation

The primary disadvantage of FNA for primary bone sarcomas is the lack of architectural information. FNA provides only cellular material, making it difficult to assess features like tumor growth pattern, invasion, and matrix production, which are critical for accurate diagnosis, grading, and subtyping of bone sarcomas (e.g., differentiating enchondroma from low-grade chondrosarcoma, or fibrous dysplasia from fibrosarcoma). Core needle biopsy provides tissue cylinders that preserve architecture.

Question 5433

Topic: 10. Pathology and Oncology

What is the primary purpose of a multidisciplinary tumor board discussion prior to biopsy for a complex musculoskeletal tumor?

. To obtain consent from the patient for the biopsy.
. To decide on the specific type of anesthesia for the biopsy.
. To ensure optimal biopsy planning (site, technique) that preserves future definitive treatment options and to integrate clinical, radiological, and pathological insights.
. To estimate the financial cost of the entire treatment plan.
. To provide a forum for junior residents to present cases.

Correct Answer & Explanation

. To ensure optimal biopsy planning (site, technique) that preserves future definitive treatment options and to integrate clinical, radiological, and pathological insights.

Explanation

The primary purpose of a multidisciplinary tumor board (MDT) discussion before biopsy for a complex musculoskeletal tumor is to ensure optimal biopsy planning. This involves integrating insights from orthopedic oncologists, radiologists, pathologists, medical oncologists, and radiation oncologists to determine the safest and most diagnostic biopsy approach that will not compromise future definitive treatment (e.g., limb salvage surgery, radiation fields). It helps avoid errors in biopsy placement and ensures the biopsy yields the most useful information for treatment planning.

Question 5434

Topic: 10. Pathology and Oncology

A biopsy for a suspected adamantinoma of the tibia is planned. Which characteristic of adamantinoma should influence the biopsy technique?

. It is typically highly vascular, requiring pre-embolization.
. It is often multifocal within the tibia, requiring multiple biopsies.
. It is a purely lytic lesion, so targeting soft tissue is important.
. It frequently presents with skip lesions, requiring careful staging.
. It is a biphasic tumor with epithelial and osteofibrous components, requiring adequate tissue for diagnosis.

Correct Answer & Explanation

. It is a biphasic tumor with epithelial and osteofibrous components, requiring adequate tissue for diagnosis.

Explanation

Adamantinoma is a rare, low-grade malignant primary bone tumor characterized by biphasic histology, consisting of epithelial and osteofibrous components. Accurate diagnosis requires obtaining adequate tissue to identify both components. This means a core needle biopsy should aim for sufficient tissue volume, and potentially multiple cores, to capture the heterogeneous nature of the tumor. While it is often purely lytic, targeting the soft tissue component might be insufficient without also sampling the bone. It's not typically highly vascular to require routine embolization.

Question 5435

Topic: 10. Pathology and Oncology

A biopsy is performed on a suspected bone lesion, and the pathology report suggests 'reactive process'. However, the patient's C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) are elevated, and there is a history of fever. What is the MOST likely cause of this discrepancy, and what should be done?

. The biopsy missed the tumor, and the patient has an infection. Repeat biopsy with culture.
. The reactive process is causing the fever and elevated markers. Observe.
. The patient has a primary bone tumor with a superimposed infection. Treat infection first.
. The biopsy was adequate, and the patient has a systemic inflammatory condition. Refer to rheumatology.
. The CRP/ESR are false positives; rely on biopsy.

Correct Answer & Explanation

. The biopsy missed the tumor, and the patient has an infection. Repeat biopsy with culture.

Explanation

The scenario describes a significant clinicopathologic and laboratory discordance. 'Reactive process' on biopsy in the context of fever, elevated inflammatory markers (CRP, ESR), and a suspicious bone lesion strongly suggests that the biopsy either missed an underlying tumor (sampling error) or an infection was present but not adequately cultured or identified. The most appropriate next step is to repeat the biopsy, ensuring samples are sent for both histopathology and comprehensive microbiological cultures (aerobic, anaerobic, fungal, AFB). It's crucial not to miss a bone infection (osteomyelitis) or a tumor. The patient could also have a tumor with a superimposed infection, which necessitates both diagnosis and treatment.

Question 5436

Topic: 10. Pathology and Oncology

What is the role of prophylactic internal fixation prior to biopsy in a patient with a large lytic lesion in a weight-bearing bone?

. It is never indicated, as it complicates the biopsy procedure.
. It is indicated if there is an imminent risk of pathological fracture to stabilize the bone before biopsy.
. It is only indicated if the biopsy itself causes a fracture.
. It is a standard procedure for all large lytic lesions.
. It is indicated to prevent tumor dissemination.

Correct Answer & Explanation

. It is indicated if there is an imminent risk of pathological fracture to stabilize the bone before biopsy.

Explanation

Prophylactic internal fixation (e.g., intramedullary nail) may be indicated prior to biopsy for large lytic lesions in weight-bearing bones (like the femur) if there is an imminent risk of pathological fracture. The goal is to stabilize the bone, prevent a fracture during or immediately after the biopsy, and ensure the patient can remain mobile. This strategy allows the biopsy to be performed safely and prevents the acute morbidity of a pathological fracture, which complicates subsequent definitive treatment. It does not prevent tumor dissemination.

Question 5437

Topic: 10. Pathology and Oncology

A 10-year-old child presents with a lesion in the proximal humerus. Biopsy reveals small round blue cells. Which molecular diagnostic test is MOST crucial for differentiating between Ewing sarcoma and other small round blue cell tumors?

. FISH (Fluorescence In Situ Hybridization) for EWSR1 gene rearrangement.
. Immunohistochemistry for CD99 (MIC2).
. Karyotyping for chromosomal abnormalities.
. PCR for MYC amplification.
. Next-generation sequencing for broad gene panels.

Correct Answer & Explanation

. FISH (Fluorescence In Situ Hybridization) for EWSR1 gene rearrangement.

Explanation

While CD99 (MIC2) immunohistochemistry is highly sensitive for Ewing sarcoma, it is not specific. Definitive diagnosis of Ewing sarcoma relies on the detection of specific chromosomal translocations involving the EWSR1 gene (most commonly t(11;22)(q24;q12)) or FUS gene. FISH for EWSR1 gene rearrangement is the most crucial and definitive molecular diagnostic test for confirming Ewing sarcoma and differentiating it from other small round blue cell tumors. Karyotyping is more general, PCR for MYC is not specific to Ewing, and NGS might be used but FISH is the targeted gold standard here.

Question 5438

Topic: 10. Pathology and Oncology

After a core needle biopsy, the biopsy tract should ideally be managed how to minimize oncologic risk?

. Left open to drain.
. Closed with absorbable sutures.
. Left to heal by secondary intention.
. Included in the definitive surgical resection margin en bloc with the tumor.
. Treated with local radiation.

Correct Answer & Explanation

. Included in the definitive surgical resection margin en bloc with the tumor.

Explanation

The biopsy tract, especially for suspected malignant lesions, is considered contaminated with tumor cells. Therefore, it is critical that the entire biopsy tract be included within the definitive surgical resection margin and removed en bloc with the primary tumor. This minimizes the risk of local recurrence from tumor seeding. Leaving it open, simple closure, or radiation of the tract alone are not oncologically sound approaches for a primary high-grade bone tumor.

Question 5439

Topic: 10. Pathology and Oncology

When performing a biopsy of a suspected soft tissue sarcoma, why is it crucial to avoid transgressing multiple fascial compartments?

. To prevent neurovascular injury.
. To limit the spread of local anesthetic.
. To minimize the risk of muscle atrophy.
. To preserve uncontaminated tissue planes for subsequent limb-salvage surgery.
. To reduce post-operative swelling.

Correct Answer & Explanation

. To preserve uncontaminated tissue planes for subsequent limb-salvage surgery.

Explanation

Transgressing multiple fascial compartments during a soft tissue sarcoma biopsy is a major error. It contaminates additional fascial compartments with tumor cells, effectively upgrading the tumor to involve a larger area. This significantly complicates subsequent limb-salvage surgery, as a much wider and more extensive resection would be required to achieve clear margins, potentially making limb salvage impossible. Preserving uncontaminated tissue planes is paramount for successful oncologic resection.

Question 5440

Topic: 10. Pathology and Oncology

A 75-year-old patient presents with a lytic lesion in the sacrum. A percutaneous biopsy is performed. Which complication is a particular concern due to the proximity of the biopsy site to the bowel and urinary tract?

. Spinal cord injury.
. Pathological fracture.
. Intraperitoneal hemorrhage.
. Infection/fistula formation.
. Tumor seeding.

Correct Answer & Explanation

. Infection/fistula formation.

Explanation

For sacral biopsies, especially those involving the anterior sacrum, a significant concern is injury to the bowel or urinary bladder, which can lead to severe infection and/or fistula formation. Careful image guidance and appropriate approach selection are critical to avoid these structures. While spinal cord injury and tumor seeding are concerns for any spinal tumor biopsy, and pathological fracture is a general bone biopsy risk, infection/fistula formation from bowel/bladder injury is a specific and devastating complication of sacral biopsies.

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