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10. Pathology and Oncology MCQs

Practice Set 311 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 6201

Topic: 10. Pathology and Oncology

A 28-year-old male presents with a deep mass attached to the plantar fascia of the foot. Biopsy shows nests of polygonal cells with clear cytoplasm and melanin pigment. This tumor is a translocation-associated sarcoma. Which immunohistochemical marker is most likely positive?

. Desmin
. Cytokeratin
. CD34
. S-100
. Smooth Muscle Actin (SMA)

Correct Answer & Explanation

. S-100

Explanation

Clear cell sarcoma (melanoma of soft parts) is derived from neural crest cells and typically stains positive for melanocytic markers such as S-100, HMB-45, and Melan-A. It is driven by the t(12;22) translocation.

Question 6202

Topic: 10. Pathology and Oncology

A 22-year-old male presents with a painless, ulcerating nodule on his volar forearm, initially misdiagnosed as an infection. Biopsy confirms epithelioid sarcoma. What is a defining characteristic of the clinical behavior of this specific sarcoma?

. It has a high propensity for lymphatic spread.
. It only metastasizes to the bone.
. It typically spontaneously regresses.
. It is highly sensitive to isolated limb perfusion.
. It exhibits skip lesions strictly within the muscle belly.

Correct Answer & Explanation

. It has a high propensity for lymphatic spread.

Explanation

Epithelioid sarcoma is unique among soft tissue sarcomas because of its significant tendency to spread via regional lymph nodes. Clinically, it often presents in the distal extremities of young adults as a superficial, ulcerating mass.

Question 6203

Topic: 10. Pathology and Oncology

A 6-year-old boy presents with a rapidly enlarging mass in his forearm. A biopsy confirms rhabdomyosarcoma. Which of the following features represents a favorable prognostic factor?

. Presence of the t(2;13) translocation
. Alveolar histological subtype
. Age older than 10 years at diagnosis
. Embryonal histological subtype
. Tumor size greater than 5 cm

Correct Answer & Explanation

. Embryonal histological subtype

Explanation

In pediatric rhabdomyosarcoma, the embryonal subtype generally portends a better prognosis than the alveolar subtype. The alveolar subtype is often driven by the t(2;13) or t(1;13) translocations and is more aggressive.

Question 6204

Topic: 10. Pathology and Oncology

A 60-year-old female develops an aggressive soft tissue sarcoma in her axilla 10 years following lumpectomy and radiation for breast cancer.

According to Cahan's criteria for diagnosing radiation-induced sarcoma, which of the following must be met?

. The sarcoma must occur within 2 years of the radiation therapy.
. The sarcoma must have identical histology to the original primary tumor.
. The patient must be documented to have a p53 mutation.
. The new tumor must arise entirely outside the field of previous radiation.
. The sarcoma must arise within the irradiated field after a latent period.

Correct Answer & Explanation

. The sarcoma must arise within the irradiated field after a latent period.

Explanation

Cahan's criteria state that a radiation-induced sarcoma must arise within the previously irradiated field, have a different histology from the primary tumor, and occur after a substantial latent period (typically >3-5 years).

Question 6205

Topic: 10. Pathology and Oncology

A 55-year-old male has a deep intramuscular fatty mass in the thigh. Biopsy shows mature adipocytes with occasional enlarged, hyperchromatic stromal cells. Amplification of which of the following genes is the molecular hallmark distinguishing this atypical lipomatous tumor from a benign lipoma?

. MDM2
. c-MYC
. HER2
. EWSR1
. FLI1

Correct Answer & Explanation

. MDM2

Explanation

Atypical lipomatous tumors/well-differentiated liposarcomas are characterized by the amplification of the MDM2 and CDK4 genes on chromosome 12q. Benign lipomas typically lack this amplification.

Question 6206

Topic: 10. Pathology and Oncology

A 35-year-old female presents with a painless mass in her foot. Biopsy shows nests of pale-staining cells with prominent nucleoli. Immunohistochemistry is positive for S100 and HMB-45. What is the characteristic chromosomal translocation associated with this tumor?

. t(X;18) SYT-SSX
. t(12;22) EWS-ATF1
. t(12;16) FUS-DDIT3
. t(2;13) PAX3-FOXO1
. t(11;22) EWS-FLI1

Correct Answer & Explanation

. t(12;22) EWS-ATF1

Explanation

Clear cell sarcoma (melanoma of soft parts) characteristically presents in the foot or ankle of young adults. It is positive for S100 and HMB-45, and is driven by the t(12;22) EWS-ATF1 translocation.

Question 6207

Topic: 10. Pathology and Oncology

A 45-year-old male is diagnosed with myxoid liposarcoma of the proximal thigh. Which of the following imaging modalities is uniquely recommended for staging this patient prior to definitive management?

. Brain MRI
. Sentinel lymph node biopsy
. Total spine MRI
. PET-CT scan
. Bone scintigraphy

Correct Answer & Explanation

. Total spine MRI

Explanation

Myxoid liposarcoma has a unique propensity to metastasize to other soft tissues and extrapulmonary bone sites, particularly the spine. A total spine MRI is routinely recommended for staging to rule out occult spinal metastases.

Question 6208

Topic: 10. Pathology and Oncology

A 30-year-old male presents with a deep thigh mass.

Biopsy confirms synovial sarcoma. Which of the following describes the most common chromosomal abnormality associated with this tumor?

. t(12;16) FUS-DDIT3
. t(X;18) SYT-SSX
. t(11;22) EWS-FLI1
. t(2;13) PAX3-FOXO1
. t(17;22) COL1A1-PDGFB

Correct Answer & Explanation

. t(X;18) SYT-SSX

Explanation

Synovial sarcoma is strongly associated with the t(X;18) translocation, resulting in the SYT-SSX fusion gene. It commonly presents as a deep, frequently calcified mass near a joint in young adults.

Question 6209

Topic: 10. Pathology and Oncology

A 55-year-old male undergoes marginal excision of a massive, painless thigh mass. Histology demonstrates a pleomorphic spindle cell neoplasm arranged in a storiform pattern with giant cells. No specific translocations are found, and immunohistochemistry is non-contributory. What is the most likely diagnosis?

. Myxofibrosarcoma
. Undifferentiated pleomorphic sarcoma
. Dermatofibrosarcoma protuberans
. Synovial sarcoma
. Liposarcoma

Correct Answer & Explanation

. Undifferentiated pleomorphic sarcoma

Explanation

Undifferentiated pleomorphic sarcoma (UPS), formerly known as malignant fibrous histiocytoma (MFH), is a diagnosis of exclusion. It classically presents with a storiform pattern and highly pleomorphic cells, lacking a specific fusion gene or distinct immunohistochemical marker.

Question 6210

Topic: 10. Pathology and Oncology

A 35-year-old male presents with a large, painless thigh mass. Biopsy confirms myxoid liposarcoma with the characteristic t(12;16) translocation. In addition to a chest CT, which of the following imaging modalities is most appropriate for staging this specific sarcoma?

. Sentinel lymph node biopsy
. MRI of the entire spine
. Brain MRI
. PET scan only
. Bone marrow biopsy

Correct Answer & Explanation

. MRI of the entire spine

Explanation

Myxoid liposarcoma has a unique propensity to metastasize to extrapulmonary sites, particularly the bone and spine. Therefore, whole-spine MRI or whole-body MRI is recommended for accurate staging to detect osseous metastases.

Question 6211

Topic: 10. Pathology and Oncology

An MRI of a 40-year-old female with chronic hip pain reveals multiple intra-articular loose bodies with a "ring and arc" pattern of calcification.

What is the most feared complication of long-standing primary disease of this type?

. Malignant transformation to synovial sarcoma
. Malignant transformation to secondary chondrosarcoma
. Progression to pigmented villonodular synovitis
. Rapid systemic metastasis to the lungs
. Avascular necrosis of the femoral head

Correct Answer & Explanation

. Malignant transformation to secondary chondrosarcoma

Explanation

Primary synovial chondromatosis involves benign cartilaginous metaplasia of the synovium. Rarely, long-standing cases can undergo malignant transformation into secondary chondrosarcoma, which should be suspected if there is rapid clinical deterioration or aggressive imaging features.

Question 6212

Topic: 10. Pathology and Oncology

A 30-year-old female presents with recurrent, bloody knee effusions. MRI shows a diffuse synovial process with blooming artifact on gradient-echo sequences. Biopsy confirms a condition characterized by a t(1;2) translocation. What is the mechanism of action of the targeted medical therapy recently approved for refractory cases of this disease?

. Tyrosine kinase inhibitor targeting c-KIT
. Monoclonal antibody against RANKL
. Small molecule inhibitor of CSF1R
. Inhibitor of the mTOR pathway
. Monoclonal antibody targeting PD-1

Correct Answer & Explanation

. Small molecule inhibitor of CSF1R

Explanation

Tenosynovial giant cell tumor (formerly PVNS) is driven by a t(1;2) translocation causing Colony Stimulating Factor 1 (CSF1) overexpression. Pexidartinib, a CSF1R inhibitor, is approved for advanced or refractory cases.

Question 6213

Topic: 10. Pathology and Oncology

A 28-year-old female presents with a deep, slow-growing mass in the plantar aspect of her foot. Biopsy reveals a neoplasm with nested cells separated by fibrous septa. Immunohistochemistry is positive for S-100 and HMB-45. What is the characteristic chromosomal translocation associated with this tumor?

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

Correct Answer & Explanation

. t(12;22)

Explanation

Clear cell sarcoma (melanoma of soft parts) is characterized by the t(12;22) translocation resulting in the EWSR1-ATF1 fusion gene. It commonly presents in the distal extremities of young adults and stains positive for melanocytic markers.

Question 6214

Topic: 10. Pathology and Oncology
A 35-year-old male undergoes wide excision of a nodular skin plaque on his trunk. Pathology demonstrates a storiform pattern of spindle cells that strongly express CD34 but are negative for Factor XIIIa. Which targeted therapy is most appropriate for metastatic or unresectable forms of this tumor?
. Imatinib
. Denosumab
. Pexidartinib
. Doxorubicin
. Pazopanib

Correct Answer & Explanation

. Imatinib

Explanation

Dermatofibrosarcoma protuberans (DFSP) is driven by a t(17;22) translocation resulting in COL1A1-PDGFB fusion. Unresectable or metastatic cases are treated with Imatinib, a tyrosine kinase inhibitor.

Question 6215

Topic: 10. Pathology and Oncology

Certain soft tissue sarcomas have a higher propensity for regional lymph node metastasis and require specialized staging. Which of the following soft tissue sarcomas most warrants evaluation of the regional lymph nodes?

. Undifferentiated pleomorphic sarcoma
. Myxofibrosarcoma
. Rhabdomyosarcoma
. Liposarcoma
. Fibrosarcoma

Correct Answer & Explanation

. Rhabdomyosarcoma

Explanation

Sarcomas that frequently metastasize to lymph nodes can be remembered by the mnemonic SCARE: Synovial, Clear cell, Angiosarcoma, Rhabdomyosarcoma, and Epithelioid sarcoma. These tumors necessitate vigilant regional lymph node evaluation.

Question 6216

Topic: 10. Pathology and Oncology

A 26-year-old male presents with a deep mass near the knee joint. Biopsy reveals a biphasic tumor with both epithelial and spindle cell components. Cytogenetics confirm a t(X;18) translocation. Which of the following immunohistochemical markers is typically positive in the epithelial component of this tumor?

. S-100 only
. Cytokeratin and EMA
. Desmin and Myogenin
. MDM2 and CDK4
. CD34 and STAT6

Correct Answer & Explanation

. Cytokeratin and EMA

Explanation

Synovial sarcoma is characterized by the t(X;18) SYT-SSX translocation. Despite its name, it does not arise from synovium, and its epithelial component typically stains positive for Cytokeratin and Epithelial Membrane Antigen (EMA).

Question 6217

Topic: 10. Pathology and Oncology

A 50-year-old female presents with a slow-growing thigh mass. Biopsy reveals a "staghorn" vascular pattern and spindle cells. Immunohistochemistry is strongly positive for STAT6 and CD34. What is the specific molecular driver for this neoplasm?

. NAB2-STAT6 fusion
. COL1A1-PDGFB fusion
. FUS-DDIT3 fusion
. SS18-SSX1 fusion
. PAX3-FOXO1 fusion

Correct Answer & Explanation

. NAB2-STAT6 fusion

Explanation

Solitary fibrous tumors (formerly hemangiopericytomas) are defined by an inversion on chromosome 12 leading to the NAB2-STAT6 fusion gene. This makes nuclear STAT6 expression a highly sensitive and specific immunohistochemical marker.

Question 6218

Topic: 10. Pathology and Oncology

A 4-year-old boy presents with progressive restricted neck movement and firm soft tissue swelling on his back. Physical exam reveals bilateral short great toes with hallux valgus. What is the most appropriate next step in management?

. Incisional biopsy of the soft tissue mass
. Wide excision of the mass
. Genetic testing for ACVR1 gene mutation
. Administration of intravenous bisphosphonates
. Marginal excision to restore mobility

Correct Answer & Explanation

. Incisional biopsy of the soft tissue mass

Explanation

Fibrodysplasia ossificans progressiva (FOP) is caused by an ACVR1 mutation and presents with congenital great toe malformations and progressive heterotopic ossification. Any surgical intervention or biopsy is strictly contraindicated as it will trigger explosive heterotopic bone formation.

Question 6219

Topic: 10. Pathology and Oncology
A 60-year-old male has an 8 cm high-grade undifferentiated pleomorphic sarcoma (UPS) resected from his anterior thigh. Pathology margins are reported as < 1 mm but negative. He receives postoperative adjuvant radiotherapy. What is the primary benefit of adding radiotherapy in this clinical scenario?
. It eliminates the need for future systemic chemotherapy.
. It improves overall patient survival.
. It decreases the rate of local recurrence.
. It prevents the development of pulmonary metastases.
. It converts a marginal excision into a wide oncologic margin.

Correct Answer & Explanation

. It decreases the rate of local recurrence.

Explanation

Adjuvant radiotherapy in the treatment of soft tissue sarcomas significantly decreases the rate of local recurrence, particularly for large, high-grade, or deep tumors with close margins. However, it does not universally improve overall survival or prevent distant metastasis.

Question 6220

Topic: 10. Pathology and Oncology
A 35-year-old female with a history of numerous café-au-lait spots, axillary freckling, and Lisch nodules presents with rapid enlargement and new onset pain in a long-standing peripheral nerve mass. What is the most likely diagnosis of this newly changing lesion?
. Schwannoma
. Neurofibroma
. Malignant peripheral nerve sheath tumor (MPNST)
. Synovial sarcoma
. Desmoid tumor

Correct Answer & Explanation

. Malignant peripheral nerve sheath tumor (MPNST)

Explanation

Patients with Neurofibromatosis type 1 (NF1) have an increased risk of developing MPNSTs, which often arise from pre-existing plexiform neurofibromas. Rapid enlargement, new pain, or neurologic deficits in a stable mass strongly suggest malignant transformation.

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