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10. Pathology and Oncology MCQs

Practice Set 271 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 5401

Topic: 10. Pathology and Oncology

A 7-year-old presents with a painful swelling around the knee. Radiographs reveal a large, multiloculated lesion in the proximal tibia metaphysis, expanding the cortex and with a thinned sclerotic rim. Which of the following features would be atypical for a Non-Ossifying Fibroma and prompt consideration of other diagnoses?

. Lesion located in the metaphysis.
. Eccentric location within the bone.
. Well-defined sclerotic border.
. Extensive periosteal reaction or soft tissue mass.
. Multiloculated appearance.

Correct Answer & Explanation

. Extensive periosteal reaction or soft tissue mass.

Explanation

While NOFs can be painful if large or fractured, and show cortical thinning and expansion, an extensive periosteal reaction or a significant soft tissue mass would be atypical and raise concern for a more aggressive lesion (e.g., osteosarcoma, Ewing's sarcoma, osteomyelitis) or other pathology like aneurysmal bone cyst (ABC) with soft tissue extension. NOFs usually have a well-defined sclerotic rim and are contained within the bone, showing minimal or no periosteal reaction unless fractured.

Question 5402

Topic: 10. Pathology and Oncology

Which of the following conditions is considered a distinct entity but has some histological and radiographic overlap with NOF, particularly in the tibia, leading to a differential consideration?

. Osteosarcoma
. Adamantinoma
. Aneurysmal Bone Cyst
. Osteofibrous Dysplasia
. Chondroblastoma

Correct Answer & Explanation

. Osteofibrous Dysplasia

Explanation

Osteofibrous Dysplasia (OFD) is a rare, benign fibro-osseous lesion that predominantly affects the cortex of the tibia and occasionally the fibula. It shares some radiographic and histological features (fibrous tissue, lytic areas) with NOF, making it a key differential diagnosis, especially in the tibia. However, OFD contains characteristic epithelial nests (malassezia-like epithelial rests), distinguishing it definitively. Adamantinoma is a rare malignant tumor often associated with OFD in the tibia. Osteosarcoma and chondroblastoma are distinct. ABC is often more expansile and cystic.

Question 5403

Topic: 10. Pathology and Oncology

If a Non-Ossifying Fibroma is incidentally found in an adult (e.g., 40-year-old), what is the most likely scenario?

. It represents a newly developed aggressive lesion requiring immediate biopsy.
. It is a residual, 'burnt-out' lesion from childhood that did not fully resolve.
. It is a sign of underlying systemic malignancy.
. It indicates a high risk of developing Jaffe-Campanacci Syndrome in adulthood.
. It is an error in diagnosis, as NOFs do not occur in adults.

Correct Answer & Explanation

. It is a residual, 'burnt-out' lesion from childhood that did not fully resolve.

Explanation

While NOFs are primarily lesions of childhood and adolescence, it is possible for a 'burnt-out' or quiescent NOF to persist as a residual sclerotic lesion (or even a small lucent area) into adulthood, having failed complete spontaneous resolution. It would not typically represent a newly developed or aggressive lesion, nor is it a sign of systemic malignancy or the onset of Jaffe-Campanacci syndrome in adulthood. While rare, it's not an error in diagnosis, but rather a persistent benign lesion.

Question 5404

Topic: 10. Pathology and Oncology

A 60-year-old patient presents with a lytic lesion in the T10 vertebral body. MRI shows significant epidural extension. Prior to biopsy, which additional diagnostic study is MOST crucial for surgical planning?

. Bone scan (Tc-99m MIBI)
. Electromyography (EMG)
. CT angiogram of the thoracic spine
. Myelogram
. Fluoroscopic dynamic flexion-extension views of the thoracic spine

Correct Answer & Explanation

. CT angiogram of the thoracic spine

Explanation

For a lytic lesion in a vertebral body with significant epidural extension, especially one that may be highly vascular (e.g., metastatic renal cell carcinoma, thyroid carcinoma, hemangioma), a CT angiogram is crucial. It helps identify feeding vessels, assess vascularity, and map out the relationship to major vessels, which is vital for planning a safe biopsy and potential embolization prior to definitive surgery. This minimizes the risk of catastrophic hemorrhage. Myelogram is largely replaced by MRI, EMG evaluates nerve function but not vascularity, and bone scans provide metabolic activity but not anatomical detail for vascular planning. Flexion-extension views assess stability, which is important but secondary to immediate hemorrhage risk for a biopsy.

Question 5405

Topic: 10. Pathology and Oncology

During a core needle biopsy of a suspected tumor, there is pulsatile bleeding despite local anesthetic with epinephrine. What is the most immediate and appropriate next step?

. Continue with the biopsy quickly to minimize bleeding time.
. Apply direct pressure and abort the biopsy.
. Inject more epinephrine directly into the bleeding site.
. Advance the biopsy needle further to tamponade the vessel.
. Attempt to visualize the bleeding vessel with fluoroscopy or ultrasound and coagulate.

Correct Answer & Explanation

. Apply direct pressure and abort the biopsy.

Explanation

Pulsatile bleeding during a biopsy indicates arterial injury. The most immediate and appropriate step is to apply direct pressure to the bleeding site and abort the biopsy. Continuing the biopsy risks further injury and uncontrolled hemorrhage. Injecting more epinephrine may not be effective for an arterial bleed and could mask the problem. Advancing the needle blindly is dangerous. Visualization and coagulation might be considered in a controlled surgical setting, but for an interventional radiology-guided percutaneous biopsy, halting the procedure and managing the bleeding is paramount.

Question 5406

Topic: 10. Pathology and Oncology

A 25-year-old presents with a rapidly growing mass in the posterior thigh. MRI shows a large soft tissue mass suggestive of sarcoma. A core needle biopsy is planned. What is the MOST critical anatomical consideration for incision placement?

. Placing the incision to avoid the sciatic nerve.
. Ensuring the incision is longitudinal and follows the line of muscle fibers.
. Making the incision as small as possible to minimize scarring.
. Avoiding entry into the popliteal fossa.
. Making the incision directly over the center of the mass.

Correct Answer & Explanation

. Placing the incision to avoid the sciatic nerve.

Explanation

For a mass in the posterior thigh, avoiding injury to the sciatic nerve is the paramount anatomical consideration. The sciatic nerve runs longitudinally down the posterior thigh and is highly vulnerable during biopsy in this region. While longitudinal incisions and avoiding the popliteal fossa are important general principles, the direct risk to a major nerve takes precedence. Making the incision over the center of the mass is not always safe or appropriate if it compromises neurovascular structures or future resection.

Question 5407

Topic: 10. Pathology and Oncology

The primary role of a frozen section analysis during an open biopsy for a suspected bone sarcoma is to:

. Provide a definitive diagnosis of the tumor type and grade.
. Confirm the presence of viable tumor tissue and adequacy of the specimen.
. Assess tumor margins for definitive excision.
. Determine the need for immediate limb amputation.
. Identify specific genetic translocations.

Correct Answer & Explanation

. Confirm the presence of viable tumor tissue and adequacy of the specimen.

Explanation

During an open biopsy, the primary role of frozen section analysis is to confirm the presence of viable tumor tissue and ensure the adequacy of the specimen for definitive histological diagnosis. It helps avoid 'dry taps' or biopsies that only yield necrotic or reactive tissue. Frozen section is generally not reliable for definitive diagnosis, grading, or margin assessment in complex sarcomas, nor for genetic analysis, but it provides crucial intraoperative feedback on whether representative tissue has been obtained.

Question 5408

Topic: 10. Pathology and Oncology

Which of the following types of bone lesions is most likely to be definitively diagnosed by Fine Needle Aspiration (FNA) biopsy alone?

. Osteosarcoma
. Chondrosarcoma (low-grade)
. Giant Cell Tumor of Bone
. Ewing Sarcoma
. Metastatic carcinoma (e.g., from breast or prostate)

Correct Answer & Explanation

. Metastatic carcinoma (e.g., from breast or prostate)

Explanation

FNA biopsy is often sufficient for definitive diagnosis of metastatic carcinoma, especially when the primary tumor is known. Metastatic lesions are typically monomorphic, making cytologic interpretation relatively straightforward. For primary bone tumors like osteosarcoma, chondrosarcoma (especially low-grade, which requires assessment of matrix and cellularity), Ewing sarcoma (which benefits from molecular studies), and Giant Cell Tumor (which requires assessment of stromal cells), core needle biopsy or open biopsy providing architectural information is usually preferred for definitive diagnosis.

Question 5409

Topic: 10. Pathology and Oncology

A biopsy is planned for a suspected high-grade sarcoma in the mid-shaft of the femur. The patient has significant surrounding muscle edema and a large extraosseous component. Which of the following techniques is MOST appropriate to ensure accurate biopsy targeting?

. Fluoroscopic guidance using plain X-ray.
. Ultrasound guidance.
. CT guidance.
. Blind biopsy based on anatomical landmarks.
. Open biopsy without imaging.

Correct Answer & Explanation

. CT guidance.

Explanation

For a deep bone lesion with a significant extraosseous component and surrounding edema, CT guidance is generally considered the most accurate method for biopsy targeting. It provides excellent spatial resolution and clearly delineates bone, soft tissue, and tumor boundaries, allowing precise needle placement. Fluoroscopy is less precise for soft tissue components. Ultrasound can be useful for superficial soft tissue masses, but its penetration and visualization for deep bone tumors with surrounding edema might be limited. Blind biopsy is unacceptable for deep, complex lesions. Open biopsy without imaging guidance risks missing the target and compromising planes.

Question 5410

Topic: 10. Pathology and Oncology

What is the primary reason for performing a bone marrow biopsy and aspiration in patients with suspected bone lesions, even if a primary bone tumor is already suspected?

. To rule out chronic infection.
. To assess for systemic bone involvement by leukemia or lymphoma or staging of other malignancies.
. To obtain sufficient material for cytogenetic analysis of the primary lesion.
. To evaluate red blood cell production.
. To determine bone mineral density.

Correct Answer & Explanation

. To assess for systemic bone involvement by leukemia or lymphoma or staging of other malignancies.

Explanation

Bone marrow biopsy and aspiration are critical for assessing systemic involvement, particularly in the workup of suspected leukemia, lymphoma, or multiple myeloma, which can present as solitary bone lesions. It also plays a role in staging other malignancies (e.g., neuroblastoma) or determining the extent of metastatic disease. It is not typically performed to rule out infection, evaluate red blood cell production, or determine bone mineral density in this context.

Question 5411

Topic: 10. Pathology and Oncology

Which of the following measures is MOST effective in preventing tumor cell seeding along the biopsy tract during a core needle biopsy for suspected sarcoma?

. Using a cutting needle rather than an aspiration needle.
. Applying cautery along the entire biopsy tract during withdrawal.
. Using a coaxial biopsy system where the outer cannula remains in place during specimen retrieval.
. Performing the biopsy under general anesthesia.
. Administering neoadjuvant chemotherapy prior to biopsy.

Correct Answer & Explanation

. Using a coaxial biopsy system where the outer cannula remains in place during specimen retrieval.

Explanation

Using a coaxial biopsy system is highly effective in preventing tumor cell seeding. The outer cannula creates a clean, protected tract through which multiple samples can be taken without re-contaminating superficial tissues with tumor cells. Each core is retrieved through the cannula, minimizing contact with surrounding healthy tissue. While using cautery might help, it's not as universally effective as a coaxial system. A cutting needle is for obtaining cores, not preventing seeding. General anesthesia has no bearing on seeding. Neoadjuvant chemotherapy is given after biopsy and diagnosis.

Question 5412

Topic: 10. Pathology and Oncology

A patient with a suspected high-grade osteosarcoma of the proximal tibia undergoes an open incisional biopsy. During closure, the MOST important step to facilitate future limb-salvage surgery is:

. Using absorbable sutures for skin closure to minimize foreign body reaction.
. Placing a surgical drain to prevent hematoma formation.
. Marking the biopsy incision with permanent sutures or metallic clips to identify the tract for en bloc resection.
. Applying a large bulky dressing to compress the wound.
. Administering a prophylactic dose of antibiotics post-operatively.

Correct Answer & Explanation

. Marking the biopsy incision with permanent sutures or metallic clips to identify the tract for en bloc resection.

Explanation

When an open incisional biopsy is performed for a suspected sarcoma, it is critical to mark the biopsy incision and tract. This is typically done with permanent sutures (e.g., non-absorbable monofilament) or metallic clips placed at the biopsy site or within the tract. These markers allow the definitive surgical team to accurately identify and resect the entire contaminated biopsy tract en bloc with the tumor, preventing recurrence from seeded cells. While drains, appropriate sutures, and antibiotics are good surgical practices, they are not specific to identifying the biopsy tract for subsequent resection.

Question 5413

Topic: 10. Pathology and Oncology

Which of the following diagnostic imaging modalities is typically NOT utilized for direct guidance during bone tumor biopsy?

. Fluoroscopy
. Computed Tomography (CT)
. Ultrasound
. Magnetic Resonance Imaging (MRI)
. Positron Emission Tomography (PET)

Correct Answer & Explanation

. Positron Emission Tomography (PET)

Explanation

Positron Emission Tomography (PET) is used for staging and assessing metabolic activity of tumors, but it does not provide real-time anatomical guidance for needle placement during biopsy. Fluoroscopy, CT, ultrasound, and even MRI (though less commonly due to cost, accessibility, and hardware compatibility issues) can all be used for direct image guidance during biopsy procedures to ensure accurate targeting.

Question 5414

Topic: 10. Pathology and Oncology

A 68-year-old male presents with severe back pain and a pathological compression fracture of L2. Imaging shows multiple sclerotic and lytic lesions throughout the spine and pelvis. What is the MOST likely primary diagnosis requiring biopsy for confirmation?

. Multiple Myeloma
. Metastatic Prostate Carcinoma
. Osteosarcoma
. Paget's Disease of Bone
. Ewing Sarcoma

Correct Answer & Explanation

. Metastatic Prostate Carcinoma

Explanation

Given the patient's age, gender, and presentation with widespread sclerotic and lytic lesions, metastatic prostate carcinoma is the most likely diagnosis. Prostate cancer commonly metastasizes to bone, producing mixed lytic and sclerotic lesions. Multiple myeloma typically causes purely lytic lesions ('punched-out'). Osteosarcoma and Ewing sarcoma are generally tumors of younger individuals, and Paget's disease presents differently. While biopsy would confirm, based on epidemiology and imaging, prostate cancer metastasis is top of the differential.

Question 5415

Topic: 10. Pathology and Oncology

A core needle biopsy of a suspected low-grade chondrosarcoma in the pelvis is performed. The pathologist reports 'atypical cartilage, not clearly malignant'. What is the most appropriate next step?

. Initiate radiation therapy.
. Prescribe NSAIDs and observe for 3 months.
. Repeat the biopsy with an open incisional technique to obtain a larger, more representative sample.
. Proceed with wide surgical resection.
. Refer for chemotherapy.

Correct Answer & Explanation

. Repeat the biopsy with an open incisional technique to obtain a larger, more representative sample.

Explanation

Biopsy of low-grade chondrosarcomas can be challenging due to their histological similarity to enchondromas, especially with small core needle biopsies which may suffer from sampling error. A diagnosis of 'atypical cartilage, not clearly malignant' or 'indeterminate' often warrants a larger, more representative sample, typically obtained via an open incisional biopsy. This allows the pathologist to assess the architecture and cellularity more thoroughly. Proceeding with wide resection or initiating systemic therapy based on an indeterminate biopsy is premature. Observation is inappropriate for a potentially malignant lesion.

Question 5416

Topic: 10. Pathology and Oncology

Which of the following statements regarding the timing of biopsy for a suspected bone sarcoma is MOST accurate?

. Biopsy should always be performed before any advanced imaging (MRI, CT) to avoid artifacts.
. Biopsy should ideally be performed after full staging workup and multidisciplinary tumor board discussion, but before neoadjuvant therapy.
. Biopsy should be performed immediately upon suspicion to expedite diagnosis and treatment.
. Biopsy should be delayed until the patient experiences significant pain or pathological fracture.
. Biopsy should only be performed if the tumor is resectable.

Correct Answer & Explanation

. Biopsy should ideally be performed after full staging workup and multidisciplinary tumor board discussion, but before neoadjuvant therapy.

Explanation

The most accurate timing for a biopsy of a suspected bone sarcoma is after a complete imaging workup (X-ray, MRI, CT, potentially PET) and often after a multidisciplinary tumor board discussion. This comprehensive understanding allows for optimal biopsy planning, ensuring it does not compromise future limb salvage. The biopsy is performed before initiation of neoadjuvant chemotherapy, as a definitive diagnosis is required for treatment planning. Performing it before advanced imaging would be a mistake, as imaging guides the biopsy. Delaying for symptoms or only if resectable are incorrect approaches.

Question 5417

Topic: 10. Pathology and Oncology

A biopsy tract infection occurs after a core needle biopsy for a high-grade sarcoma. How should this complication influence the definitive surgical plan?

. It typically has no impact on the definitive surgical plan, as antibiotics will clear the infection.
. It necessitates delaying surgery until the infection is completely resolved and may require a wider margin of resection.
. It indicates that amputation is now the only viable limb-salvage option.
. It means the biopsy was performed incorrectly and must be repeated in a different location.
. It only impacts the choice of post-operative antibiotics, not the resection plan.

Correct Answer & Explanation

. It necessitates delaying surgery until the infection is completely resolved and may require a wider margin of resection.

Explanation

A biopsy tract infection is a serious complication. It necessitates delaying definitive surgery until the infection is completely resolved. Furthermore, the presence of infection could potentially lead to wider tumor spread or compromise tissue planes, thus often requiring a wider margin of resection of the surrounding contaminated tissue to achieve local control. It does not automatically necessitate amputation but makes limb salvage more challenging. Repeating the biopsy or simply changing antibiotics are insufficient responses to a biopsy tract infection in the context of a high-grade sarcoma.

Question 5418

Topic: 10. Pathology and Oncology

When performing a biopsy of a suspected bone tumor, what is the most important reason to maintain meticulous hemostasis?

. To prevent post-operative wound dehiscence.
. To improve visibility during the biopsy procedure.
. To minimize hematoma formation that could obscure tumor boundaries and spread tumor cells.
. To reduce the need for blood transfusions.
. To prevent infection at the biopsy site.

Correct Answer & Explanation

. To minimize hematoma formation that could obscure tumor boundaries and spread tumor cells.

Explanation

Maintaining meticulous hemostasis during and after a biopsy is crucial primarily to minimize hematoma formation. A significant hematoma can obscure tissue planes, making subsequent definitive surgery more challenging by distorting anatomical landmarks. More importantly, hematomas can spread tumor cells into previously uncontaminated areas, potentially compromising surgical margins and increasing the risk of local recurrence. While it also helps visibility, prevents dehiscence, and reduces transfusion needs, the oncological implications of hematoma are paramount.

Question 5419

Topic: 10. Pathology and Oncology

A 40-year-old female presents with a lesion in the greater trochanter of the femur, appearing aggressive on MRI. What type of biopsy approach is generally preferred to minimize morbidity and preserve tissue planes for future definitive surgery?

. Direct open incisional biopsy through a transverse approach.
. CT-guided core needle biopsy through a longitudinal approach.
. Excisional biopsy.
. Fine Needle Aspiration (FNA).
. Arthroscopic biopsy.

Correct Answer & Explanation

. CT-guided core needle biopsy through a longitudinal approach.

Explanation

For deep, aggressive bone lesions like those in the greater trochanter, a CT-guided core needle biopsy performed through a well-planned longitudinal approach is generally preferred. This technique minimizes trauma, preserves surrounding tissue planes, and allows the entire biopsy tract to be easily resected with the definitive tumor. A transverse open incision would contaminate a larger area and complicate future resection. Excisional biopsy is inappropriate for aggressive lesions. FNA may not yield sufficient diagnostic tissue. Arthroscopic biopsy is generally for intra-articular lesions, not trochanteric ones.

Question 5420

Topic: 10. Pathology and Oncology

Which of the following is the MOST significant advantage of image-guided core needle biopsy over open incisional biopsy for a suspected sarcoma?

. Lower cost.
. Faster procedure time.
. Reduced risk of tumor cell dissemination and better preservation of oncologic surgical planes.
. Ability to obtain a larger tissue sample.
. No need for general anesthesia.

Correct Answer & Explanation

. Reduced risk of tumor cell dissemination and better preservation of oncologic surgical planes.

Explanation

The most significant advantage of image-guided core needle biopsy over open incisional biopsy for suspected sarcoma is the reduced risk of tumor cell dissemination (seeding) and better preservation of oncologic surgical planes. By creating a small, straight, and well-defined tract, the core needle biopsy minimizes tissue trauma and tumor spread, allowing for easier and more complete en bloc resection of the biopsy tract with the tumor during definitive surgery. Open biopsies, especially if poorly planned, can contaminate wider areas and compromise subsequent limb salvage.

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