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10. Pathology and Oncology MCQs

Practice Set 257 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 5121

Topic: 10. Pathology and Oncology

MRI of the shoulder shows prominent fatty infiltration and atrophy of the supraspinatus muscle. This finding could be related to:

. Muscle tumor
. Rotator cuff tear
. Liposarcoma
. Peripheral nerve tumor
. Subcutaneous lipoma

Correct Answer & Explanation

. Rotator cuff tear

Explanation

Fatty infiltration and atrophy of the rotator cuff muscles, particularly the supraspinatus, are classic MRI findings associated with chronic rotator cuff tears, especially large or massive tears. This reflects disuse atrophy and chronic denervation due to the tear, rather than a primary tumor process like a liposarcoma or other muscle tumor.

Question 5122

Topic: 10. Pathology and Oncology

A patient undergoes wide local excision for a high-grade myxoid liposarcoma of the thigh. What is the most appropriate imaging strategy for long-term follow-up to detect local recurrence or metastasis?

. Clinical examination only
. Yearly X-rays of the thigh
. Serial ultrasound of the surgical site
. MRI of the surgical bed and CT chest/abdomen/pelvis at regular intervals
. PET-CT every 6 months

Correct Answer & Explanation

. MRI of the surgical bed and CT chest/abdomen/pelvis at regular intervals

Explanation

High-grade sarcomas, including myxoid liposarcoma, necessitate rigorous long-term follow-up due to significant risks of local recurrence and distant metastasis. MRI of the surgical bed is essential for detecting subtle local recurrences. CT of the chest, abdomen, and pelvis (depending on the primary site and specific metastatic patterns of the subtype) is crucial for screening for distant metastases, particularly to the lungs. The frequency of imaging typically decreases over time (e.g., every 3-6 months for the first 2-3 years, then annually up to 5-10 years).

Question 5123

Topic: Soft Tissue Tumors & Metastasis

A patient presents with a large, rapidly growing retroperitoneal dedifferentiated liposarcoma. What is the cornerstone of treatment?

. Systemic chemotherapy alone
. Radiation therapy alone
. Aggressive surgical resection with negative margins
. Targeted therapy
. Observation and palliative care

Correct Answer & Explanation

. Aggressive surgical resection with negative margins

Explanation

For dedifferentiated liposarcomas (DDLPS), particularly in challenging locations like the retroperitoneum, aggressive surgical resection with the goal of achieving negative margins remains the cornerstone of treatment. While chemotherapy and radiation therapy may play important neoadjuvant or adjuvant roles to improve resectability or reduce local recurrence, complete surgical removal offers the best chance for local control and improved survival. DDLPS is often resistant to chemotherapy alone.

Question 5124

Topic: Soft Tissue Tumors & Metastasis

Which subtype of liposarcoma, often considered a high-grade variant, is characterized by a significant proportion of primitive, small round cells in addition to myxoid areas and plexiform capillaries?

. Well-differentiated liposarcoma
. Pleomorphic liposarcoma
. Myxoid liposarcoma with a round cell component
. Dedifferentiated liposarcoma
. Spindle cell lipoma

Correct Answer & Explanation

. Myxoid liposarcoma with a round cell component

Explanation

Myxoid liposarcoma is graded based on its cellularity, specifically the percentage of round cells within the myxoid stroma. A significant 'round cell component' (e.g., >5% or >25% depending on the specific grading system) indicates a higher-grade myxoid liposarcoma, which has a worse prognosis and higher metastatic potential than its low-grade counterpart. These round cells are primitive, undifferentiated cells.

Question 5125

Topic: 10. Pathology and Oncology

A rare, benign, fatty tumor that arises from brown fat and is typically found in the neck, axilla, or mediastinum is called:

. Lipoma
. Lipoblastoma
. Hibernoma
. Myxoid lipoma
. Spindle cell lipoma

Correct Answer & Explanation

. Hibernoma

Explanation

Hibernoma is a rare, benign tumor originating from the vestigial remnants of brown fat (multilocular adipocytes). It commonly occurs in regions where brown fat is normally present in early life, such as the neck, axilla, mediastinum, retroperitoneum, and thigh. Lipoblastoma is a pediatric tumor of immature fat cells. The other options are variants of typical white fat lipomas.

Question 5126

Topic: 10. Pathology and Oncology

Which of the following benign fatty tumors is classically known to be painful?

. Conventional lipoma
. Hibernoma
. Spindle cell lipoma
. Angiolipoma
. Pleomorphic lipoma

Correct Answer & Explanation

. Angiolipoma

Explanation

Angiolipomas are benign lipomatous tumors characterized by a prominent vascular component (mature capillary-sized vessels) and frequently present as painful or tender nodules, a distinguishing feature from conventional lipomas, which are typically painless.

Question 5127

Topic: 10. Pathology and Oncology

What is the MOST crucial distinguishing feature on MRI between a benign lipoma and an atypical lipomatous tumor (ALT)/well-differentiated liposarcoma?

. Size greater than 5 cm
. Deep-seated location
. Presence of uniform fat signal
. Presence of thick (>2mm) enhancing septa or non-lipomatous nodules
. Perilesional edema

Correct Answer & Explanation

. Presence of thick (>2mm) enhancing septa or non-lipomatous nodules

Explanation

While size, depth, and perilesional edema can raise suspicion, the most crucial and specific distinguishing features on MRI between a benign lipoma and an ALT/WDLPS are the presence of thick (>2mm), nodular, or enhancing septa, or the presence of non-lipomatous solid enhancing nodules within the fatty mass. Benign lipomas typically have thin or no septa, which are non-enhancing, and no solid nodules.

Question 5128

Topic: Soft Tissue Tumors & Metastasis

Myxoid liposarcoma commonly occurs in which anatomical location?

. Subcutaneous tissue of the trunk
. Head and neck region
. Retroperitoneum
. Deep soft tissues of the lower extremities (e.g., thigh)
. Hands and feet

Correct Answer & Explanation

. Deep soft tissues of the lower extremities (e.g., thigh)

Explanation

Myxoid liposarcoma is the second most common subtype of liposarcoma and has a strong predilection for the deep soft tissues of the lower extremities, particularly the thigh. While well-differentiated and dedifferentiated liposarcomas are frequently found in the retroperitoneum, myxoid liposarcomas are predominantly limb-based.

Question 5129

Topic: 10. Pathology and Oncology

Which of the following statements regarding liposarcoma grades and metastatic potential is most accurate?

. All liposarcoma subtypes have a high metastatic potential.
. Well-differentiated liposarcoma commonly metastasizes to regional lymph nodes.
. Myxoid liposarcoma is the only subtype with a risk of bone metastases.
. High-grade liposarcomas (dedifferentiated, pleomorphic, high-grade myxoid) have a significant risk of distant metastasis, primarily to the lungs.
. Low-grade liposarcomas frequently metastasize but have excellent survival rates.

Correct Answer & Explanation

. High-grade liposarcomas (dedifferentiated, pleomorphic, high-grade myxoid) have a significant risk of distant metastasis, primarily to the lungs.

Explanation

High-grade liposarcomas, including dedifferentiated, pleomorphic, and high-grade myxoid variants, carry a significant risk of distant metastasis, with the lungs being the most common site. While myxoid liposarcoma is notable for its propensity to metastasize to unusual sites like bone and brain, it is not theonlysubtype with this risk, especially if other subtypes dedifferentiate. Well-differentiated liposarcoma/ALT do not metastasize unless they dedifferentiate. Lymph node metastases are rare for most soft tissue sarcomas.

Question 5130

Topic: Soft Tissue Tumors & Metastasis

What is the characteristic histological appearance of a lipoblast, a key diagnostic cell in liposarcoma?

. Small, round cell with scant cytoplasm and hyperchromatic nucleus
. Spindle-shaped cell with wavy nuclei and eosinophilic cytoplasm
. Large, polygonal cell with abundant clear cytoplasm and central nucleus
. Multivacuolated cell with scalloped, eccentric nucleus, resembling a signet ring
. Foamy macrophage with lipid droplets

Correct Answer & Explanation

. Multivacuolated cell with scalloped, eccentric nucleus, resembling a signet ring

Explanation

A true lipoblast, a hallmark cell of liposarcoma, is a neoplastic immature fat cell. It is characterized by one or more cytoplasmic lipid vacuoles that indent and scallop the nucleus. A univacuolated lipoblast has a single large vacuole pushing the nucleus to the periphery, resembling a signet ring cell, while a multivacuolated lipoblast has multiple smaller vacuoles, all indenting the nucleus. This distinguishes it from mature adipocytes or lipid-laden macrophages.

Question 5131

Topic: Soft Tissue Tumors & Metastasis

In which scenario might primary amputation be considered as the initial treatment for a liposarcoma?

. Small (<3cm), low-grade superficial liposarcoma
. Large, low-grade retroperitoneal liposarcoma
. High-grade liposarcoma with no evidence of neurovascular involvement
. Extremely large, high-grade liposarcoma with extensive neurovascular involvement, where limb salvage is unlikely
. Myxoid liposarcoma after neoadjuvant chemotherapy

Correct Answer & Explanation

. Extremely large, high-grade liposarcoma with extensive neurovascular involvement, where limb salvage is unlikely

Explanation

Limb salvage surgery is the preferred approach for most soft tissue sarcomas. However, primary amputation may be considered as the initial treatment for an extremely large, high-grade liposarcoma with extensive invasion of critical neurovascular structures or bone, where achieving negative margins with functional limb salvage is deemed impossible or would result in a limb less functional than a well-fitted prosthesis. In other scenarios, limb salvage is typically attempted first, often with neoadjuvant therapies.

Question 5132

Topic: 10. Pathology and Oncology

For a suspicious soft tissue mass, what is a key advantage of ultrasound-guided core needle biopsy over an open incisional biopsy?

. Provides a larger tissue sample
. Avoids the need for local anesthesia
. Minimizes contamination of tissue planes and facilitates future surgery
. Offers real-time pathological diagnosis
. Is more accurate for deep-seated lesions

Correct Answer & Explanation

. Minimizes contamination of tissue planes and facilitates future surgery

Explanation

A critical advantage of ultrasound-guided core needle biopsy is that it is less invasive and can be planned along the axis of the intended definitive surgical incision. This minimizes the risk of contaminating broader tissue planes, which is crucial for subsequent wide local excision to achieve oncologically clear margins without compromising a future limb salvage procedure. Open incisional biopsy, if not meticulously placed, can compromise the surgical field.

Question 5133

Topic: 10. Pathology and Oncology

In children, what is the most common benign fatty tumor that resembles adult lipoma but has a higher potential for local recurrence due to its infiltrative nature?

. Hibernoma
. Lipoblastoma
. Spindle cell lipoma
. Angiolipoma
. Pleomorphic lipoma

Correct Answer & Explanation

. Lipoblastoma

Explanation

Lipoblastoma is a benign, uncommon adipose tissue tumor primarily affecting infants and young children. It is composed of immature fat cells (lipoblasts) and mature adipocytes. It can be circumscribed or infiltrative, with the infiltrative type having a higher local recurrence rate, thus requiring careful excision, similar to adult intramuscular lipomas.

Question 5134

Topic: 10. Pathology and Oncology

Adjuvant radiotherapy is most commonly indicated in the management of soft tissue sarcomas for which of the following reasons?

. To prevent distant metastasis
. To treat positive surgical margins or reduce local recurrence risk after wide excision
. As a primary treatment for unresectable tumors
. To enhance the efficacy of systemic chemotherapy
. To improve bone density in irradiated areas

Correct Answer & Explanation

. To treat positive surgical margins or reduce local recurrence risk after wide excision

Explanation

Adjuvant (post-operative) radiotherapy is primarily used in the management of soft tissue sarcomas to improve local control. It is indicated to sterilize microscopic residual disease after surgical resection, especially in cases of close or positive surgical margins, or for large/high-grade tumors even with clear margins, to significantly reduce the risk of local recurrence. It does not prevent distant metastasis; that is the role of systemic therapy.

Question 5135

Topic: 10. Pathology and Oncology

A 55-year-old female undergoes radical resection of a large retroperitoneal dedifferentiated liposarcoma. Given the high recurrence rate, what is the most appropriate long-term surveillance strategy?

. Clinical follow-up every 6 months for 5 years, then annually.
. Annual MRI of the abdomen/pelvis and CT chest for 10 years.
. PET-CT every 6 months for life.
. CT abdomen/pelvis and chest every 3-6 months for 2-3 years, then less frequently, usually up to 10 years or more.
. Regular blood tests including tumor markers.

Correct Answer & Explanation

. CT abdomen/pelvis and chest every 3-6 months for 2-3 years, then less frequently, usually up to 10 years or more.

Explanation

Dedifferentiated liposarcomas, particularly in the retroperitoneum, have a very high rate of local recurrence and significant metastatic potential. Aggressive and prolonged surveillance with cross-sectional imaging (CT of the abdomen/pelvis and chest) at frequent intervals (e.g., every 3-6 months) for the initial 2-3 years, with intervals then gradually extended, is crucial. Surveillance typically continues for at least 10 years, and often longer, due to the potential for late recurrences. Clinical follow-up alone or less frequent imaging is inadequate for such aggressive tumors. Tumor markers are not reliable for liposarcoma surveillance.

Question 5136

Topic: Bone Tumors

Which of the following chondrosarcoma variants is characterized histologically by a biphasic pattern of small, round undifferentiated cells and islands of well-differentiated hyaline cartilage?

. Conventional chondrosarcoma.
. Dedifferentiated chondrosarcoma.
. Mesenchymal chondrosarcoma.
. Clear cell chondrosarcoma.
. Juxtacortical chondrosarcoma.

Correct Answer & Explanation

. Mesenchymal chondrosarcoma.

Explanation

Mesenchymal chondrosarcoma is classically described by its biphasic histological pattern: a primitive, small round cell component resembling Ewing sarcoma or hemangiopericytoma, and distinct islands of hyaline cartilage. This unique histology contributes to its more aggressive behavior and responsiveness to chemotherapy, unlike conventional chondrosarcoma. Other variants do not share this specific biphasic morphology.

Question 5137

Topic: 10. Pathology and Oncology

A 25-year-old female presents with a painful mass on the surface of her distal femur. Radiographs show a broad-based sessile lesion arising from the cortical surface with a cartilaginous cap. There is no evidence of medullary invasion. Biopsy confirms juxtacortical chondrosarcoma. What is the most appropriate surgical approach?

. Intralesional curettage.
. Wide en bloc resection.
. Marginal excision including the underlying cortex.
. Amputation.
. Radiation therapy as primary treatment.

Correct Answer & Explanation

. Marginal excision including the underlying cortex.

Explanation

Juxtacortical (or periosteal) chondrosarcoma, although often low-grade, still requires complete excision. Marginal excision including the underlying cortex (cortical saucerization) is typically sufficient to achieve clear margins for these lesions, as they originate from the periosteum and tend to grow outwards rather than invading the medullary cavity significantly. Wide en bloc resection would be overly aggressive for many cases if a marginal excision is feasible with a clear margin. Intralesional curettage is inadequate. Amputation is generally not indicated. Radiation therapy is not a primary treatment for resectable chondrosarcoma.

Question 5138

Topic: 10. Pathology and Oncology
Which of the following statements regarding the grading of conventional chondrosarcoma is most accurate?
. Grade I tumors have a high metastatic potential.
. Grading is primarily based on mitotic activity and cellular pleomorphism.
. Grade III tumors are considered benign but locally aggressive.
. The presence of necrosis automatically upstages a tumor to Grade III.
. Grading is predictive of response to chemotherapy.

Correct Answer & Explanation

. Grading is primarily based on mitotic activity and cellular pleomorphism.

Explanation

The grading of conventional chondrosarcoma (I, II, III) is a crucial prognostic indicator. It is primarily based on cellularity, nuclear size and atypia, and the presence of myxoid changes. Mitotic figures, while present in higher grades, are often scarce even in Grade II. Necrosis, when present, is a strong indicator of Grade III disease and contributes to the diagnosis. Grade I tumors have very low metastatic potential. Grade III tumors are malignant and highly aggressive with significant metastatic potential. Grading for conventional chondrosarcoma is generally not predictive of chemotherapy response, as most conventional chondrosarcomas are chemoresistant.

Question 5139

Topic: 10. Pathology and Oncology

A 50-year-old male with a history of a solitary osteochondroma in the distal femur presents with new onset pain and an enlarging mass. Radiographs show irregular cortical thickening and a lucency within the cartilaginous cap. What is the most critical measurement on imaging to suggest malignant transformation?

. Overall size of the osteochondroma.
. Width of the stalk.
. Presence of a bursa over the lesion.
. Thickness of the cartilaginous cap exceeding 2-3 cm in adults.
. Presence of a growth plate within the osteochondroma.

Correct Answer & Explanation

. Thickness of the cartilaginous cap exceeding 2-3 cm in adults.

Explanation

For a solitary osteochondroma, a cartilaginous cap thickness exceeding 2-3 cm in adults is a strong indicator of malignant transformation to secondary peripheral chondrosarcoma. In children, cap thickness up to 2 cm can be normal. Other factors like increasing size, new pain, erosion of adjacent bone, or irregular calcifications are also suggestive, but cap thickness is a key diagnostic criterion on imaging. The width of the stalk and presence of a bursa are not direct indicators of malignancy. A growth plate within an osteochondroma is normal.

Question 5140

Topic: 10. Pathology and Oncology

Regarding the surgical management of chondrosarcoma, why is tumor contamination of the surgical field a significant concern?

. It increases the risk of systemic metastasis.
. It prevents successful limb salvage.
. It significantly increases the risk of local recurrence.
. It always necessitates adjuvant radiation therapy.
. It makes histological diagnosis more challenging.

Correct Answer & Explanation

. It significantly increases the risk of local recurrence.

Explanation

Chondrosarcomas are known for their propensity for local recurrence, especially if tumor cells are spilled or left behind in the surgical field. Tumor contamination significantly increases the risk of local recurrence, which can be more aggressive and challenging to treat. While systemic metastasis can occur, contamination's primary and most direct impact is on local control. It does not inherently prevent limb salvage, but it complicates it. Adjuvant radiation is not always necessitated, and histological diagnosis is typically performed preoperatively.

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