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10. Pathology and Oncology MCQs

Practice Set 255 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 5081

Topic: Bone Tumors

When is an osteochondroma considered 'active' or 'growing'?

. When the patient reports any pain
. When the cartilage cap is visible on X-ray
. When the patient is skeletally immature and the lesion increases in size
. When it forms a bursa
. When it causes neurological symptoms

Correct Answer & Explanation

. When the patient is skeletally immature and the lesion increases in size

Explanation

An osteochondroma is considered 'active' or 'growing' when it increases in size in a skeletally immature patient, as its growth is linked to the adjacent physis. Once the physis fuses at skeletal maturity, the osteochondroma typically stops growing. Pain, visible cartilage cap (not visible on X-ray), bursa formation, or neurological symptoms are complications or features, not direct indicators of continued growth of the bone itself.

Question 5082

Topic: Bone Tumors

A rare but serious complication of osteochondromas, particularly in the popliteal fossa, can be the formation of a pseudoaneurysm. What clinical finding would be most suggestive of this complication?

. Progressive foot drop
. Acute, severe pain with swelling and pulsation
. Chronic, dull aching pain with stiffness
. Skin discoloration with associated numbness
. Audible crepitus with movement

Correct Answer & Explanation

. Acute, severe pain with swelling and pulsation

Explanation

A pseudoaneurysm formation due to irritation or injury of an artery (e.g., popliteal artery in the popliteal fossa) by an osteochondroma presents as acute, severe pain, rapidly enlarging swelling, and a palpable pulsatile mass. This is a surgical emergency. Foot drop implies nerve compression. Chronic pain suggests bursitis or other mechanical issues. Skin discoloration and numbness are non-specific. Crepitus suggests bursitis or fracture.

Question 5083

Topic: 10. Pathology and Oncology

Which histological feature is characteristic of the cartilage cap of a benign osteochondroma?

. Invasion into adjacent soft tissues
. Hypercellularity with nuclear atypia and disorganized growth
. Well-organized hyaline cartilage with columnar arrangement of chondrocytes at the base, similar to a growth plate
. Numerous mitotic figures
. Presence of myxoid change and spindle cells

Correct Answer & Explanation

. Well-organized hyaline cartilage with columnar arrangement of chondrocytes at the base, similar to a growth plate

Explanation

The cartilage cap of a benign osteochondroma histologically resembles a normal growth plate. It consists of well-organized hyaline cartilage with a columnar arrangement of chondrocytes at its base, undergoing endochondral ossification. Features like invasion, hypercellularity with atypia, numerous mitoses, or myxoid change are indicative of malignant transformation (chondrosarcoma).

Question 5084

Topic: 10. Pathology and Oncology

A 16-year-old boy has an osteochondroma of the distal ulna causing significant ulnar deviation of the wrist. This deformity is known as 'Madelung-like deformity.' What is the primary surgical goal in addressing this?

. Cosmetic improvement only
. Preservation of growth at the distal ulna
. Correction of angular deformity and improvement of wrist function
. Prevention of malignant transformation
. Amputation to prevent progression

Correct Answer & Explanation

. Correction of angular deformity and improvement of wrist function

Explanation

In a case of Madelung-like deformity caused by a distal ulnar osteochondroma, the primary surgical goal is to correct the angular deformity, restore proper wrist alignment, and improve wrist function, which may involve excision of the osteochondroma and possibly an osteotomy or guided growth procedure. While cosmetic improvement may occur, function is paramount. Prevention of malignant transformation is not the primary goal here. Amputation is not indicated. Preserving growth at an already pathologically growing physis is secondary to correcting deformity.

Question 5085

Topic: Bone Tumors

Which diagnostic challenge might arise when an osteochondroma is located near a joint with extensive bursal formation?

. Difficulty distinguishing it from an enchondroma
. Mimicking a soft tissue mass without a clear bony component on imaging
. Confusion with an osteoid osteoma due to similar pain patterns
. Misdiagnosis as a stress fracture
. Inability to perform MRI due to artifact

Correct Answer & Explanation

. Mimicking a soft tissue mass without a clear bony component on imaging

Explanation

An osteochondroma with extensive bursal formation can present as a soft, fluctuant, or cystic-appearing mass, which might obscure the underlying bony component clinically and sometimes on less detailed imaging. This can lead to the lesion being mistaken for a purely soft tissue mass or a cystic lesion without appreciating its underlying bony origin. Enchondromas are intramedullary. Osteoid osteoma pain is typically nocturnal. Stress fractures are different entities. MRI is generally well-tolerated.

Question 5086

Topic: 10. Pathology and Oncology

A 30-year-old male presents with a new onset of severe pain, warmth, and swelling around a known osteochondroma in his shoulder girdle. MRI reveals a large, lobulated soft tissue mass with high T2 signal intensity and a thick, irregular cartilage cap measuring 4 cm. What is the most appropriate definitive management for this patient?

. Observation and NSAIDs
. Intralesional steroid injection
. Radiation therapy
. Surgical en bloc resection with wide margins
. Percutaneous thermal ablation

Correct Answer & Explanation

. Surgical en bloc resection with wide margins

Explanation

The clinical presentation (new severe pain, rapid growth in an adult) combined with MRI findings (large, lobulated soft tissue mass, thick and irregular 4 cm cartilage cap) are highly suggestive of malignant transformation to a secondary peripheral chondrosarcoma. For chondrosarcoma, the definitive treatment is surgical en bloc resection with wide margins to achieve local control. Percutaneous biopsy should precede this to confirm diagnosis and grade, but assuming confirmed, this is the definitive treatment. Other options are inappropriate for suspected malignancy.

Question 5087

Topic: 10. Pathology and Oncology

A 62-year-old male presents with a progressively enlarging, deep-seated soft tissue mass in his thigh over the past year. It is firm to palpation and minimally tender. What clinical feature is most concerning for malignancy in this scenario?

. Location in the subcutaneous tissue
. Presence of mild tenderness
. Slow growth over one year
. Deep-seated location and firm consistency
. Size less than 5 cm

Correct Answer & Explanation

. Deep-seated location and firm consistency

Explanation

Deep-seated lesions (>3 cm from the skin surface) and firm consistency, especially with progressive enlargement, are significant red flags for malignancy in soft tissue masses. While slow growth can occur with low-grade sarcomas, any growth warrants suspicion when combined with other concerning features. Subcutaneous location is generally less concerning, and tenderness is not a reliable differentiator for malignancy.

Question 5088

Topic: 10. Pathology and Oncology
A T1-weighted MRI of a suspected lipoma shows a well-circumscribed lesion with uniform high signal intensity, identical to subcutaneous fat. However, there are also thin, non-enhancing septa (<2mm thick). What is the most appropriate interpretation of these findings?
. Definitely a benign lipoma, no further action needed.
. Highly suggestive of a well-differentiated liposarcoma.
. Suggestive of an atypical lipomatous tumor (ALT)/well-differentiated liposarcoma, requiring careful follow-up or biopsy.
. Consistent with a necrotic lipoma.
. Indeterminate, but unlikely to be malignant.

Correct Answer & Explanation

. Suggestive of an atypical lipomatous tumor (ALT)/well-differentiated liposarcoma, requiring careful follow-up or biopsy.

Explanation

While uniform fat signal is characteristic of a benign lipoma, the presence of internal septations, particularly if they are thick (>2mm), nodular, or enhancing, significantly raises suspicion for atypical lipomatous tumor (ALT) / well-differentiated liposarcoma (WDLPS). Even thin septa, when combined with other subtle features or clinical suspicion, necessitate closer scrutiny. The term ALT is synonymous with WDLPS when arising in the extremities or trunk wall, indicating a locally aggressive tumor with no metastatic potential unless dedifferentiated.

Question 5089

Topic: 10. Pathology and Oncology

A biopsy of a soft tissue mass reveals mature adipocytes with significant variation in cell size, scattered atypical stromal cells with hyperchromatic nuclei, and rare lipoblasts. No evidence of pleomorphic lipoblasts or non-lipogenic sarcoma components is seen. These findings are most consistent with which diagnosis?

. Benign lipoma
. Hibernoma
. Myxoid liposarcoma
. Well-differentiated liposarcoma (WDL)
. Pleomorphic liposarcoma

Correct Answer & Explanation

. Well-differentiated liposarcoma (WDL)

Explanation

Well-differentiated liposarcoma (WDL) is characterized by a proliferation of mature adipocytes with architectural disarray, often demonstrating variation in cell size, along with atypical stromal cells (often hyperchromatic spindle cells) and, at times, univacuolated or multivacuolated lipoblasts. The absence of pleomorphic lipoblasts and high-grade non-lipogenic components helps differentiate it from dedifferentiated or pleomorphic liposarcoma. Benign lipomas do not exhibit these atypical features.

Question 5090

Topic: 10. Pathology and Oncology

Which of the following genetic alterations is most commonly associated with well-differentiated liposarcoma and atypical lipomatous tumor (ALT)?

. t(X;18)(p11.2;q11.2) translocation
. MDM2 and CDK4 gene amplification
. FUS-DDIT3 fusion gene
. EWSR1-FLI1 translocation
. BRAF V600E mutation

Correct Answer & Explanation

. MDM2 and CDK4 gene amplification

Explanation

Amplification of the MDM2 and CDK4 genes, located on chromosome 12q13-15, is the hallmark genetic alteration found in well-differentiated liposarcoma (WDLPS) and atypical lipomatous tumor (ALT). This genetic marker is critical for distinguishing WDLPS/ALT from benign lipomas, which lack these amplifications. The other listed translocations are characteristic of different sarcoma types (Synovial sarcoma, Myxoid liposarcoma, Ewing sarcoma).

Question 5091

Topic: 10. Pathology and Oncology

A 45-year-old patient presents with a 10 cm, deep-seated, well-circumscribed fatty mass in the thigh, confirmed as an atypical lipomatous tumor (ALT) by core needle biopsy. What is the most appropriate management?

. Observation with serial imaging
. Intralesional corticosteroid injection
. Marginal excision with careful follow-up
. Wide local excision with negative margins
. Adjuvant radiotherapy followed by marginal excision

Correct Answer & Explanation

. Wide local excision with negative margins

Explanation

Atypical lipomatous tumor (ALT), when located in the extremities or trunk wall, is considered a low-grade malignancy that is locally aggressive with a high risk of local recurrence if not adequately excised, but lacks metastatic potential (unless it dedifferentiates). Therefore, wide local excision with negative margins is the standard of care to achieve local control and minimize recurrence. Marginal excision is insufficient. Observation or injections are inappropriate. Adjuvant radiotherapy is typically considered for positive margins or higher-grade sarcomas.

Question 5092

Topic: 10. Pathology and Oncology

On ultrasound, which feature of a fatty mass is most indicative of a benign lipoma rather than a liposarcoma?

. Heterogeneous echogenicity
. Presence of color Doppler flow
. Well-defined encapsulation
. Fascial plane infiltration
. Size greater than 5 cm

Correct Answer & Explanation

. Heterogeneous echogenicity

Explanation

Benign lipomas typically appear as well-defined, encapsulated, hyperechoic masses with posterior acoustic enhancement, often parallel to the skin. Heterogeneous echogenicity, significant color Doppler flow (indicating increased vascularity), fascial plane infiltration, and larger size (>5 cm) are all features that can raise suspicion for liposarcoma on ultrasound, although imaging findings alone are not definitive for differentiation.

Question 5093

Topic: 10. Pathology and Oncology

A patient is diagnosed with a large, retroperitoneal well-differentiated liposarcoma. What is the primary concern regarding its behavior and prognosis?

. High risk of distant metastasis
. Low risk of local recurrence after complete excision
. Potential for dedifferentiation and local aggression
. Sensitivity to chemotherapy
. Rapid growth leading to early symptoms

Correct Answer & Explanation

. Potential for dedifferentiation and local aggression

Explanation

Retroperitoneal liposarcomas, even those histologically classified as well-differentiated (WDLPS), have a high propensity for local recurrence and, more significantly, for dedifferentiation into a higher-grade sarcoma. This dedifferentiation confers metastatic potential and significantly worsens prognosis. While they can grow large before symptoms due to anatomical space, local recurrence and dedifferentiation are the primary concerns. WDLPS is generally not highly sensitive to conventional chemotherapy.

Question 5094

Topic: 10. Pathology and Oncology

A 35-year-old presents with painless, recurrent knee swelling. MRI reveals a villous, frond-like proliferation of the synovium with fat signal intensity, particularly in the suprapatellar pouch. What is the most likely diagnosis?

. Synovial chondromatosis
. Pigmented villonodular synovitis (PVNS)
. Lipoma arborescens
. Rheumatoid arthritis
. Hoffa's disease

Correct Answer & Explanation

. Lipoma arborescens

Explanation

Lipoma arborescens is a rare, benign condition characterized by a diffuse villous lipomatous proliferation of the synovial membrane, most commonly affecting the knee joint (suprapatellar pouch). The MRI findings of villous, frond-like synovial proliferation demonstrating fat signal intensity are pathognomonic. Synovial chondromatosis involves cartilaginous metaplasia, PVNS involves hemosiderin deposition (low signal on MRI), and rheumatoid arthritis is an inflammatory arthritis, not a fatty proliferation.

Question 5095

Topic: 10. Pathology and Oncology

A large retroperitoneal fatty tumor exhibits areas of well-differentiated liposarcoma alongside distinct, high-grade non-lipogenic sarcomatous components on histology. This finding is characteristic of which subtype of liposarcoma?

. Myxoid liposarcoma
. Round cell liposarcoma
. Pleomorphic liposarcoma
. Dedifferentiated liposarcoma
. Spindle cell lipoma

Correct Answer & Explanation

. Dedifferentiated liposarcoma

Explanation

Dedifferentiated liposarcoma (DDLPS) is defined by the coexistence of a well-differentiated liposarcoma (WDLPS) component with a distinct, non-lipogenic, high-grade sarcomatous component. This dedifferentiated component is most commonly an undifferentiated pleomorphic sarcoma-like morphology, but it can also present as osteosarcoma, chondrosarcoma, or other high-grade components. This dedifferentiation dramatically increases the metastatic potential and aggressive behavior of the tumor.

Question 5096

Topic: 10. Pathology and Oncology
For a deep-seated, large (>5 cm) soft tissue mass suspected to be a liposarcoma, which imaging modality is most crucial for local staging and surgical planning?
. Plain radiography
. Ultrasound
. Computed Tomography (CT)
. Magnetic Resonance Imaging (MRI)
. PET-CT

Correct Answer & Explanation

. Magnetic Resonance Imaging (MRI)

Explanation

Magnetic Resonance Imaging (MRI) is the gold standard for local staging of soft tissue masses, providing superior soft tissue contrast and multiplanar views. It offers excellent delineation of tumor margins, its relationship to neurovascular structures, bone, and joint involvement, which are all critical for surgical planning. While CT can be useful for bony involvement and distant staging, and PET-CT for metabolic activity and distant staging, MRI provides the most comprehensive local anatomical detail.

Question 5097

Topic: 10. Pathology and Oncology

A 40-year-old presents with a rapidly growing, firm, 8 cm mass in the posterior thigh. MRI suggests a fatty tumor with nodular non-fatty components. What is the most appropriate next step in management?

. Excisional biopsy
. Immediate wide local excision
. Fine needle aspiration (FNA)
. Open incisional biopsy
. Core needle biopsy

Correct Answer & Explanation

. Core needle biopsy

Explanation

For any suspicious soft tissue mass with malignant features (rapid growth, deep location, large size, nodular non-fatty components on imaging), a pre-operative tissue diagnosis is essential to guide definitive treatment. Core needle biopsy is generally preferred over FNA due to better architectural preservation and more tissue for ancillary studies, leading to higher diagnostic accuracy. Excisional biopsy is inappropriate for potentially malignant masses as it risks contaminating tissue planes and compromising future definitive surgery. Open incisional biopsy is an option if core biopsy is inconclusive or technically difficult, but core biopsy is less invasive and usually sufficient.

Question 5098

Topic: 10. Pathology and Oncology

A biopsy shows a proliferation of primitive round and spindle cells, often arranged in cords and nests, within an abundant myxoid stroma, associated with a delicate plexiform capillary network. Lipoblasts are present. What is the most likely diagnosis?

. Nodular fasciitis
. Myxofibrosarcoma
. Myxoid lipoma
. Myxoid liposarcoma
. Lipoma with myxoid degeneration

Correct Answer & Explanation

. Myxoid liposarcoma

Explanation

Myxoid liposarcoma is characterized by a prominent myxoid matrix, a distinctive delicate plexiform capillary network (curvilinear vessels), and a proliferation of small, primitive round and spindle cells, often with univacuolated or multivacuolated lipoblasts. Myxoid lipoma is a benign entity lacking the cellularity and atypical features of liposarcoma. Myxofibrosarcoma also has a myxoid component but typically exhibits pleomorphism and lacks true lipoblasts.

Question 5099

Topic: 10. Pathology and Oncology

What is the most important component of staging a newly diagnosed high-grade liposarcoma of the thigh?

. Regional lymph node dissection
. Bone scan to rule out bone metastases
. CT scan of the chest, abdomen, and pelvis
. Comprehensive blood work including tumor markers
. Lumbar puncture for CSF analysis

Correct Answer & Explanation

. CT scan of the chest, abdomen, and pelvis

Explanation

The most common site of distant metastasis for high-grade soft tissue sarcomas, including liposarcoma, is the lungs. Therefore, a CT scan of the chest is crucial for detecting pulmonary metastases. For abdominal or retroperitoneal liposarcomas, or if metastasis to these regions is suspected, an abdominal/pelvic CT would also be included. Lymph node metastases are uncommon in most soft tissue sarcomas. Bone scans are reserved for suspected bone involvement, and tumor markers are generally not reliable for soft tissue sarcomas.

Question 5100

Topic: 10. Pathology and Oncology

A 30-year-old male is diagnosed with a 7 cm high-grade myxoid liposarcoma in the popliteal fossa. What is the most appropriate treatment strategy?

. Observation
. Neoadjuvant chemotherapy followed by wide local excision and adjuvant radiotherapy
. Primary amputation
. Marginal excision
. Intralesional steroid injection

Correct Answer & Explanation

. Neoadjuvant chemotherapy followed by wide local excision and adjuvant radiotherapy

Explanation

Myxoid liposarcoma, particularly high-grade lesions (which often contain a round cell component), is recognized for its relative sensitivity to both chemotherapy and radiotherapy. Neoadjuvant (pre-operative) chemotherapy and/or radiotherapy can help shrink the tumor, facilitate limb-salvage surgery, and improve local control. This is typically followed by wide local excision with negative margins, often with adjuvant radiotherapy to further reduce local recurrence risk. Primary amputation is reserved for unresectable tumors or those where limb salvage is functionally inferior.

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