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10. Pathology and Oncology MCQs

Practice Set 66 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 1301

Topic: Soft Tissue Tumors & Metastasis

Following initial evaluation, an MRI of the right thigh was performed. The image below shows an axial T1-weighted view of the mass. Based on the provided image and the detailed MRI description in the case, which of the following is the most accurate interpretation of the findings?

. A. A homogeneous mass with low signal intensity on T1, consistent with a myxoid liposarcoma.
. B. A predominantly fatty mass with thin septations (<2mm) and no enhancing non-fatty components, typical of a simple lipoma.
. C. A biphasic mass with macroscopic fat (high T1 signal) and distinct nodular, non-fatty components (isointense to muscle on T1), indicative of a dedifferentiated liposarcoma.
. D. A highly heterogeneous mass with significant necrosis and hemorrhage, lacking macroscopic fat, characteristic of a pleomorphic liposarcoma.
. E. A mass with serpiginous vascular channels and phleboliths, suggestive of an intramuscular hemangioma.

Correct Answer & Explanation

. C. A biphasic mass with macroscopic fat (high T1 signal) and distinct nodular, non-fatty components (isointense to muscle on T1), indicative of a dedifferentiated liposarcoma.

Explanation

Correct Answer: CThe case explicitly describes the MRI findings: 'The majority of the tumor exhibited high signal intensity on T1-weighted images that suppressed on STIR sequences, confirming the presence of macroscopic adipose tissue. However, unlike a simple benign lipoma, the mass demonstrated significant heterogeneity. There were thickened, irregular internal septations (>2 mm) and distinct nodular areas of non-fatty tissue that were isointense to muscle on T1, hyperintense on T2, and demonstrated avid, heterogeneous enhancement following gadolinium administration.' This biphasic appearance, with both fatty and solid enhancing components, is the classic radiological hallmark of an atypical lipomatous tumor or a dedifferentiated liposarcoma.Option A (A homogeneous mass with low signal intensity on T1, consistent with a myxoid liposarcoma): Myxoid liposarcomas typically lack macroscopic fat on T1 and show very high signal on T2 due to the myxoid matrix, often appearing cyst-like. This does not match the description of high T1 signal from fat.Option B (A predominantly fatty mass with thin septations (<2mm) and no enhancing non-fatty components, typical of a simple lipoma): While the mass is predominantly fatty, the description of 'thickened, irregular internal septations (>2 mm) and distinct nodular areas of non-fatty tissue that... demonstrated avid, heterogeneous enhancement' rules out a simple lipoma, which would have thin septations and no significant enhancing non-fatty components.Option D (A highly heterogeneous mass with significant necrosis and hemorrhage, lacking macroscopic fat, characteristic of a pleomorphic liposarcoma): Pleomorphic liposarcomas are typically high-grade, highly heterogeneous, and often lack visible macroscopic fat on MRI. While the mass is heterogeneous, the presence of significant macroscopic fat on T1 makes pleomorphic liposarcoma less likely as the primary radiological diagnosis.Option E (A mass with serpiginous vascular channels and phleboliths, suggestive of an intramuscular hemangioma): The MRI description does not mention serpiginous vascular channels or phleboliths (signal voids), which are characteristic of hemangiomas. Plain films also did not identify phleboliths.

Question 1302

Topic: 10. Pathology and Oncology

Given the high suspicion for a malignant soft tissue sarcoma based on the MRI findings, an image-guided core needle biopsy was planned. Which of the following is the *most* critical aspect of the biopsy strategy for this patient?

. A. Obtaining only fatty tissue samples to confirm the lipomatous nature of the lesion.
. B. Performing an open incisional biopsy to ensure adequate tissue volume.
. C. Targeting the solid, enhancing, non-fatty nodular components identified on MRI.
. D. Ensuring the biopsy tract is placed perpendicular to the long axis of the limb.
. E. Avoiding any muscle penetration to minimize post-biopsy hematoma.

Correct Answer & Explanation

. C. Targeting the solid, enhancing, non-fatty nodular components identified on MRI.

Explanation

Correct Answer: CThe most critical aspect of the biopsy strategy istargeting the solid, enhancing, non-fatty nodular components identified on MRI. The case states: 'Multiple cores were obtained using a 14-gauge coaxial system, specifically targeting the solid, enhancing, non-fatty nodular components identified on the MRI, as these areas harbor the highest grade of malignancy and dictate the overall prognosis and treatment strategy. Biopsying only the fatty components could lead to a false-negative diagnosis of a simple lipoma or under-grading the lesion as merely an atypical lipomatous tumor.'Option A (Obtaining only fatty tissue samples to confirm the lipomatous nature of the lesion): This is incorrect and dangerous. As explained in the case, biopsying only fatty components risks missing the high-grade dedifferentiated component, leading to under-diagnosis and inappropriate treatment.Option B (Performing an open incisional biopsy to ensure adequate tissue volume): While incisional biopsies provide more tissue, a well-planned core needle biopsy is generally preferred for extremity sarcomas due to lower morbidity and less risk of tumor seeding, provided it is performed by an experienced musculoskeletal radiologist. The case specifically mentions a percutaneous, ultrasound-guided core needle biopsy.Option D (Ensuring the biopsy tract is placed perpendicular to the long axis of the limb): The biopsy tract should be placed longitudinally, in line with the planned surgical incision, to ensure it can be completely excised en bloc with the tumor. A perpendicular tract would be difficult to excise completely.Option E (Avoiding any muscle penetration to minimize post-biopsy hematoma): While minimizing hematoma is important, avoidinganymuscle penetration is often impossible for deep intramuscular lesions. The key is to ensure the biopsy tract traverses only the muscle immediately adjacent to the tumor and falls entirely within the planned future surgical excision ellipse, even if it means traversing muscle.

Question 1303

Topic: Soft Tissue Tumors & Metastasis

Based on the clinical presentation, physical examination, and the MRI findings (including the image provided), which of the following diagnoses is most consistent with Mr. J.A.'s tumor?

. A. Simple Lipoma
. B. Myxoid Liposarcoma
. C. Dedifferentiated Liposarcoma
. D. Intramuscular Hemangioma
. E. Pleomorphic Liposarcoma

Correct Answer & Explanation

. C. Dedifferentiated Liposarcoma

Explanation

Correct Answer: CThe clinical and radiological findings are most consistent with aDedifferentiated Liposarcoma. The case explicitly states: 'The presence of a predominantly fatty tumor with thick septations and nodular, enhancing, non-lipomatous components is the classic radiological hallmark of an atypical lipomatous tumor or a dedifferentiated liposarcoma.' The table in the case further reinforces this, describing DDLPS as having a 'Biphasic appearance. Fatty regions adjacent to prominent, solid, non-fatty, avidly enhancing nodular components.'Option A (Simple Lipoma): A simple lipoma would be homogeneously fatty with thin septations (<2mm) and no nodular enhancement. This contradicts the MRI findings of thickened septations and enhancing non-fatty nodules.Option B (Myxoid Liposarcoma): Myxoid liposarcomas typically lack macroscopic fat on T1 and show very high T2 signal due to the myxoid matrix. The MRI here clearly shows macroscopic fat (high T1 signal).Option D (Intramuscular Hemangioma): Hemangiomas can be heterogeneous but are characterized by serpiginous vascular channels and often phleboliths (signal voids), which were not described in this case's MRI or plain films.Option E (Pleomorphic Liposarcoma): Pleomorphic liposarcomas are high-grade and typically lack visible macroscopic fat on MRI, presenting as highly heterogeneous, necrotic, and hemorrhagic masses. While this tumor has high-grade features, the prominent macroscopic fat on T1 makes pleomorphic liposarcoma less likely than dedifferentiated liposarcoma, which specifically arises from a fatty precursor.

Question 1304

Topic: 10. Pathology and Oncology

The core needle biopsy revealed a biphasic tumor with areas consistent with Well-Differentiated Liposarcoma and an abrupt transition to a high-grade, pleomorphic spindle cell proliferation. To definitively confirm the diagnosis and distinguish it from other high-grade sarcomas, which molecular finding is the diagnostic hallmark for this tumor?

. A. FUS-DDIT3 translocation (t(12;16))
. B. EWSR1 rearrangement
. C. MDM2 and CDK4 gene amplification
. D. INI1 (SMARCB1) deletion
. E. SS18-SSX fusion gene

Correct Answer & Explanation

. C. MDM2 and CDK4 gene amplification

Explanation

Correct Answer: CThe diagnostic hallmark for the ALT/WDLPS and Dedifferentiated Liposarcoma spectrum isMDM2 and CDK4 gene amplification. The case explicitly states: 'To definitively confirm the diagnosis, molecular profiling utilizing Fluorescence In Situ Hybridization was performed. The tumor cells demonstrated high-level amplification of the MDM2 (Murine Double Minute 2) and CDK4 (Cyclin-Dependent Kinase 4) genes located on chromosome 12q13-15. This molecular signature is the diagnostic hallmark of the ALT/WDLPS and Dedifferentiated Liposarcoma spectrum, distinguishing it definitively from pleomorphic liposarcoma or undifferentiated pleomorphic sarcoma.'Option A (FUS-DDIT3 translocation (t(12;16))): This translocation is characteristic of Myxoid Liposarcoma.Option B (EWSR1 rearrangement): This is the defining molecular alteration in Ewing Sarcoma and some other round cell sarcomas.Option D (INI1 (SMARCB1) deletion): This is characteristic of epithelioid sarcoma and malignant rhabdoid tumors.Option E (SS18-SSX fusion gene): This fusion gene is the diagnostic hallmark of Synovial Sarcoma.

Question 1305

Topic: 10. Pathology and Oncology
Based on the final histopathological diagnosis of Dedifferentiated Liposarcoma (FNCLCC Grade 2) and the following staging parameters: Tumor (T): >10 cm, deep to superficial fascia (T3); Node (N): No regional lymph node involvement (N0); Metastasis (M): No distant metastasis (M0). What is the correct AJCC stage for this patient's soft tissue sarcoma?
. Stage IA
. Stage IIA
. Stage IIB
. Stage IIIA
. Stage IIIB

Correct Answer & Explanation

. Stage IIIB

Explanation

According to the AJCC staging system for Soft Tissue Sarcoma of the Trunk and Extremities: T3 (tumor >10 cm and deep to the superficial fascia), N0 (no regional lymph node involvement), M0 (no distant metastasis), and G2 (FNCLCC Grade 2/intermediate-to-high grade) corresponds to Stage IIIB.

Question 1306

Topic: 10. Pathology and Oncology

The multidisciplinary tumor board recommended neoadjuvant external beam radiation therapy followed by wide surgical resection. Which of the following is a primary oncologic advantage of neoadjuvant (preoperative) radiation therapy for this patient's large, deep, high-grade dedifferentiated liposarcoma?

. A. Significantly lower risk of acute postoperative wound complications compared to adjuvant radiation.
. B. Requires a higher total radiation dose, leading to better tumor kill.
. C. Treats a smaller target volume and potentially sterilizes the reactive pseudocapsule, making surgical resection easier.
. D. Allows for immediate surgical resection without delay.
. E. It is the only effective method to preserve the sciatic nerve in such cases.

Correct Answer & Explanation

. C. Treats a smaller target volume and potentially sterilizes the reactive pseudocapsule, making surgical resection easier.

Explanation

Correct Answer: CA primary oncologic advantage of neoadjuvant radiation therapy is that ittreats a smaller target volume and potentially sterilizes the reactive pseudocapsule, making surgical resection easier. The case states: 'Neoadjuvant radiation therapy (typically 50 Gy in 25 fractions) offers several distinct oncologic advantages: it treats a smaller target volume, potentially sterilizes the reactive pseudocapsule, thickens the tumor pseudocapsule making surgical resection easier, and requires a lower total dose, thereby reducing long-term tissue fibrosis and joint stiffness.'Option A (Significantly lower risk of acute postoperative wound complications compared to adjuvant radiation): This is incorrect. The case explicitly mentions: 'However, as demonstrated by the landmark O'Sullivan trial, neoadjuvant radiation carries a significantly higher risk of major acute postoperative wound complications (up to 35%) compared to adjuvant radiation.'Option B (Requires a higher total radiation dose, leading to better tumor kill): This is incorrect. Neoadjuvant radiation typically uses alowertotal dose (e.g., 50 Gy) compared to adjuvant radiation (e.g., 60-66 Gy) because the tumor is still in situ, allowing for a smaller, more focused field. The goal is to downstage and sterilize, not necessarily to deliver a higher total dose.Option D (Allows for immediate surgical resection without delay): This is incorrect. Neoadjuvant radiationdelayssurgery by several weeks (typically 5-6 weeks for treatment plus a recovery period), which is a known drawback.Option E (It is the only effective method to preserve the sciatic nerve in such cases): While neoadjuvant radiation can help with local control and potentially facilitate nerve-sparing surgery, it is not theonlyeffective method. Surgical technique (epimesial dissection) is also crucial, and nerve preservation depends on the extent of tumor invasion, not solely on radiation.

Question 1307

Topic: 10. Pathology and Oncology

During the surgical resection, the tumor pseudocapsule was found to be densely adherent to the epineurium of the sciatic nerve. The orthopedic oncologist performed an epimesial dissection, sharply peeling the epineurium away from the intact sciatic nerve fascicles, leaving the epineurium attached to the tumor specimen. What type of surgical margin does this technique represent at the interface with the sciatic nerve?

. A. Wide (R0) margin
. B. Marginal (R1) margin
. C. Intralesional (R2) margin
. D. Amputation margin
. E. Contaminated margin

Correct Answer & Explanation

. B. Marginal (R1) margin

Explanation

Correct Answer: BAn epimesial dissection, where the outermost layer of the nerve sheath (epineurium) is left attached to the tumor specimen, constitutes aMarginal (R1) marginat that specific anatomical location. The case states: 'This constitutes a planned marginal (R1) resection at this specific anatomical location. The rationale is that the combination of this marginal resection and the neoadjuvant radiation therapy provides excellent local control rates while preserving limb function, avoiding the devastating morbidity of a complete sciatic nerve resection.'A. Wide (R0) margin: This implies a resection with a cuff of uninvolved healthy tissue (typically >1 cm) around the entire tumor, with no microscopic tumor at the margin. While the overall goal is R0, at the nerve interface, this was not achieved due to adherence.C. Intralesional (R2) margin: This means gross tumor was left behind, or the tumor was cut through. This is not the case here, as the nerve fascicles were preserved, and the epineurium was removed with the tumor.D. Amputation margin: This refers to the margin of an amputation, which was avoided in this limb-sparing procedure.E. Contaminated margin: This term is not a standard oncologic margin classification in the same way as R0, R1, R2. It might refer to a situation where tumor cells are spilled, but the epimesial dissection is a controlled, planned technique.

Question 1308

Topic: 10. Pathology and Oncology
A 45-year-old male presents with a deep, painless thigh mass. MRI shows a predominantly fatty lesion with thin septations (<2 mm) and no enhancing non-fatty components. A biopsy confirms mature adipocytes with no atypia. In contrast, Mr. J.A.'s tumor was a Dedifferentiated Liposarcoma. Which of the following features most reliably distinguishes Mr. J.A.'s tumor from the 45-year-old male's lesion?
. The presence of a deep-seated mass.
. The absence of pain.
. The presence of macroscopic fat on MRI.
. The identification of thickened, irregular septations and enhancing non-fatty nodules on MRI, along with MDM2/CDK4 amplification.
. The patient's age at presentation.

Correct Answer & Explanation

. The identification of thickened, irregular septations and enhancing non-fatty nodules on MRI, along with MDM2/CDK4 amplification.

Explanation

Correct Answer: D. The features that most reliably distinguish Mr. J.A.'s Dedifferentiated Liposarcoma from the 45-year-old male's lesion (which appears to be a simple lipoma or atypical lipomatous tumor without dedifferentiation) are the identification of thickened, irregular septations and enhancing non-fatty nodules on MRI, along with MDM2/CDK4 amplification. These MRI findings are the classic radiological hallmark of ALT/WDLPS/DDLPS, and MDM2/CDK4 amplification is the diagnostic hallmark distinguishing it from other sarcomas and benign lesions.

Question 1309

Topic: 10. Pathology and Oncology
A 14-year-old boy is diagnosed with high-grade osteosarcoma of the distal femur. He undergoes 10 weeks of neoadjuvant chemotherapy. According to the Huvos grading system, a 'good response' to chemotherapy is defined as what percentage of tumor necrosis on the resection specimen?
. >50%
. >70%
. >90%
. 100%
. Any necrosis constitutes a good response

Correct Answer & Explanation

. >90%

Explanation

A good histologic response to neoadjuvant chemotherapy in osteosarcoma is defined as >90% tumor necrosis (Huvos grades III and IV). This is a strong independent predictor of overall survival.

Question 1310

Topic: 10. Pathology and Oncology

A 25-year-old female presents with a slow-growing, deep soft tissue mass in her popliteal fossa. Biopsy reveals a biphasic tumor with both epithelial and spindle cell components. Which of the following chromosomal translocations is most characteristic of this tumor?

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

Correct Answer & Explanation

. t(X;18)

Explanation

Synovial sarcoma is classically associated with the t(X;18) translocation, resulting in the SYT-SSX fusion gene. It often presents in young adults around the knee and may exhibit calcifications on radiographs.

Question 1311

Topic: 10. Pathology and Oncology

A 32-year-old female presents with a painless mass behind her knee. Radiographs reveal a densely ossified mass attached to the posterior cortex of the distal femur by a broad stalk. A 'string sign' is faintly visible. What is the most common histologic grade and typical management for this lesion?

. High-grade; neoadjuvant chemotherapy and wide resection
. Low-grade; wide surgical resection alone
. Low-grade; intralesional curettage and bone grafting
. High-grade; wide surgical resection alone
. Intermediate-grade; radiation therapy and wide resection

Correct Answer & Explanation

. Low-grade; wide surgical resection alone

Explanation

Parosteal osteosarcoma is typically a low-grade surface tumor presenting on the posterior distal femur. Wide surgical resection alone is the standard of care as it is insensitive to chemotherapy or radiation.

Question 1312

Topic: 10. Pathology and Oncology

A 10-year-old boy presents with a diaphyseal femur lesion showing a permeative, 'onion-skin' periosteal reaction. Biopsy reveals sheets of small round blue cells. The diagnostic translocation for this tumor primarily involves the fusion of the EWS gene with which of the following?

. FLI1 gene (t(11;22))
. SSX1 gene (t(X;18))
. CHOP gene (t(12;16))
. FOXO1 gene (t(2;13))
. c-myc amplification

Correct Answer & Explanation

. FLI1 gene (t(11;22))

Explanation

Ewing sarcoma is characterized by the t(11;22) translocation, forming the EWS-FLI1 fusion protein in about 90% of cases. It classically presents with an onion-skin periosteal reaction in the diaphysis of long bones.

Question 1313

Topic: 10. Pathology and Oncology
A 55-year-old man has a biopsy-proven Grade 2 (intermediate) chondrosarcoma of the proximal humerus. There is endosteal scalloping of >2/3 of the cortical thickness and soft tissue extension on MRI. What is the standard definitive treatment?
. Intralesional curettage, adjuvant phenol, and cementation
. Neoadjuvant chemotherapy followed by wide resection
. Wide en bloc surgical resection
. Radiation therapy followed by simple excision
. Radiofrequency ablation

Correct Answer & Explanation

. Wide en bloc surgical resection

Explanation

Grade 2 and 3 chondrosarcomas require wide en bloc resection. They are notoriously resistant to chemotherapy and radiation, unlike osteosarcoma or Ewing sarcoma.

Question 1314

Topic: 10. Pathology and Oncology

A 16-year-old boy presents with knee pain. Radiographs show a purely lytic, expansile lesion in the distal femoral metaphysis with a pathologic fracture. MRI reveals multiple fluid-fluid levels. Biopsy demonstrates high-grade malignant cells producing osteoid. What is the most appropriate initial treatment?

. Intralesional curettage and bone grafting
. Preoperative embolization followed by intralesional excision
. Neoadjuvant chemotherapy
. Primary amputation
. External beam radiation therapy

Correct Answer & Explanation

. Neoadjuvant chemotherapy

Explanation

Telangiectatic osteosarcoma presents as a hemorrhagic lesion with fluid-fluid levels mimicking an aneurysmal bone cyst. Once confirmed histologically, it is treated like classic high-grade osteosarcoma with neoadjuvant chemotherapy.

Question 1315

Topic: 10. Pathology and Oncology

A 42-year-old male complains of chronic hip pain. Radiographs reveal an epiphyseal lytic lesion in the proximal femur with central calcifications. Histology demonstrates cells with abundant clear cytoplasm and distinct boundaries. What is the most likely diagnosis?

. Chondroblastoma
. Clear cell chondrosarcoma
. Giant cell tumor
. Osteosarcoma
. Ewing sarcoma

Correct Answer & Explanation

. Clear cell chondrosarcoma

Explanation

Clear cell chondrosarcoma is a rare, low-grade malignant cartilage tumor that characteristically involves the epiphysis of long bones in middle-aged adults.

Question 1316

Topic: 10. Pathology and Oncology

A 20-year-old female presents with a mass on the anterior tibial diaphysis. Imaging reveals a predominately cartilaginous matrix tumor resting on the cortex surface, with 'hair-on-end' spicules but no medullary involvement. What is the typical histologic grade of this tumor?

. Benign
. Low-grade
. Intermediate-grade
. High-grade
. Undifferentiated

Correct Answer & Explanation

. Intermediate-grade

Explanation

Periosteal osteosarcoma is characteristically an intermediate-grade, predominately chondroblastic surface tumor. It commonly affects the anterior tibial diaphysis.

Question 1317

Topic: 10. Pathology and Oncology

A 60-year-old female treated for breast cancer with radiation 12 years ago presents with a rapidly enlarging mass in her ipsilateral scapula. Biopsy confirms high-grade osteosarcoma. Which of the following statements regarding radiation-induced sarcomas is true?

. They typically occur within 2 years of radiation therapy
. The most common histology is Ewing sarcoma
. They generally have a better prognosis than primary bone sarcomas of the same grade
. They must arise within the prior radiation field
. They are extremely sensitive to re-irradiation

Correct Answer & Explanation

. They must arise within the prior radiation field

Explanation

Criteria for radiation-induced sarcoma include arising in the previous radiation field, a latency period of usually >5 years, and histologic proof of a sarcoma. They generally carry a poorer prognosis than primary sarcomas.

Question 1318

Topic: 10. Pathology and Oncology

A 65-year-old male presents with a destructive, osteolytic lesion in his proximal humerus. A core needle biopsy is obtained. Immunohistochemistry is strongly positive for cytokeratin and negative for vimentin. What is the most likely diagnosis?

. Osteosarcoma
. Chondrosarcoma
. Metastatic carcinoma
. Ewing sarcoma
. Multiple myeloma

Correct Answer & Explanation

. Metastatic carcinoma

Explanation

Cytokeratin is a marker for epithelial cells, strongly suggesting a metastatic carcinoma. Primary bone sarcomas are tumors of mesenchymal origin and typically stain positive for vimentin.

Question 1319

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with right thigh pain and a low-grade fever. Radiographs reveal a permeative diaphyseal lesion with an 'onion-skin' periosteal reaction. A biopsy confirms small round blue cells. Which of the following chromosomal translocations is most characteristic of this tumor?

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

Correct Answer & Explanation

. t(11;22)

Explanation

This presentation is classic for Ewing sarcoma. The most common genetic abnormality in Ewing sarcoma is the t(11;22) translocation, resulting in the EWS-FLI1 fusion protein.

Question 1320

Topic: 10. Pathology and Oncology

A 24-year-old female presents with a slowly enlarging, painless mass about her knee. MRI reveals a deep soft tissue mass adjacent to the joint. Histology demonstrates a biphasic pattern of spindle cells and epithelial cells. This specific sarcoma has an unusually high propensity for metastasis to which of the following locations?

. Bone
. Lymph nodes
. Liver
. Brain
. Peritoneum

Correct Answer & Explanation

. Lymph nodes

Explanation

Synovial sarcoma typically affects young adults and often presents near joints. Along with epithelioid sarcoma, clear cell sarcoma, angiosarcoma, and rhabdomyosarcoma, it has a higher propensity for lymphatic metastasis compared to other soft tissue sarcomas.

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