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10. Pathology and Oncology MCQs

Practice Set 245 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 4881

Topic: 10. Pathology and Oncology

A 22-year-old man presents with a slow-growing, painless nodular mass on the volar aspect of his wrist. Biopsy reveals atypical epithelioid cells with central necrosis, and immunohistochemistry shows loss of INI-1 (SMARCB1) expression. This tumor has a higher-than-average propensity to metastasize to which of the following sites?

. Spleen
. Regional lymph nodes
. Contralateral extremity
. Bowel
. Thyroid gland

Correct Answer & Explanation

. Regional lymph nodes

Explanation

Epithelioid sarcoma typically affects the distal upper extremity of young adults and frequently demonstrates loss of INI-1. Unlike most soft tissue sarcomas, it has a notable propensity for regional lymph node metastasis.

Question 4882

Topic: 10. Pathology and Oncology

A 28-year-old man complains of a chronic, dull ache in his anterior leg. Radiographs reveal an eccentric, multi-loculated, 'soap-bubble' lytic lesion in the anterior tibial diaphysis. Histology shows nests of epithelial cells within a fibrous stroma. What is the most appropriate definitive management?

. Observation with serial radiographs
. Intralesional curettage, adjuvant phenol, and bone grafting
. Wide en bloc surgical resection
. Systemic chemotherapy alone
. External beam radiation therapy alone

Correct Answer & Explanation

. Wide en bloc surgical resection

Explanation

The clinical, radiographic, and histologic findings (biphasic epithelial and fibrous tissue) are diagnostic of adamantinoma, a low-grade malignant bone tumor. It is resistant to radiation and chemotherapy, making wide surgical resection the standard of care.

Question 4883

Topic: 10. Pathology and Oncology

A 24-year-old male with known Multiple Hereditary Exostoses (MHE) reports recent pain and enlargement of a previously stable lesion on his proximal medial tibia. An MRI is obtained. Which of the following findings is most concerning for malignant transformation to a secondary chondrosarcoma?

. A cartilage cap thickness greater than 2.0 cm
. Medullary continuity between the lesion and host bone
. A pedunculated morphology pointing away from the joint
. The presence of a fluid-filled bursa overlying the lesion
. Subchondral cysts in the adjacent medial tibial plateau

Correct Answer & Explanation

. A cartilage cap thickness greater than 2.0 cm

Explanation

In a skeletally mature patient with an osteochondroma, a cartilage cap thicker than 1.5 to 2.0 cm on MRI is the most reliable imaging indicator of malignant transformation to a secondary chondrosarcoma.

Question 4884

Topic: 10. Pathology and Oncology

A 6-year-old boy presents with mid-back pain. Radiographs show complete collapse of the T8 vertebral body (vertebra plana). Needle biopsy demonstrates an infiltrate of histiocytes with grooved, 'coffee-bean' nuclei mixed with eosinophils. Electron microscopy of these cells would uniquely identify which structure?

. Weibel-Palade bodies
. Birbeck granules
. Howell-Jolly bodies
. Mallory bodies
. Russell bodies

Correct Answer & Explanation

. Birbeck granules

Explanation

The presentation is classic for Langerhans Cell Histiocytosis (Eosinophilic Granuloma). The pathognomonic electron microscopy finding for Langerhans cells is the Birbeck granule, which has a distinct 'tennis-racket' shape.

Question 4885

Topic: 10. Pathology and Oncology

A 60-year-old man presents with progressive sacral pain and bowel dysfunction. MRI demonstrates a large, destructive midline sacral mass with high T2 signal. Biopsy reveals lobules of large, vacuolated 'physaliferous' cells within a myxoid stroma. Which immunohistochemical marker is highly sensitive and specific for this diagnosis?

. S-100
. CD99
. Brachyury
. Cytokeratin 7
. Smooth Muscle Actin (SMA)

Correct Answer & Explanation

. Brachyury

Explanation

The patient has a chordoma, which classically arises in the sacrum or clivus and features physaliferous cells. Nuclear expression of the transcription factor brachyury is a highly sensitive and specific marker for chordoma.

Question 4886

Topic: 10. Pathology and Oncology

A 65-year-old man presents with a painful lytic lesion in the lesser trochanter. He has a history of a radical nephrectomy for renal cell carcinoma. He is planned for a prophylactic cephalomedullary nailing. What is the most critical pre-operative step to prevent intra-operative complications?

. Administration of neoadjuvant chemotherapy
. Pre-operative angiogram and selective embolization
. Core needle biopsy of the lesion
. Intravenous administration of bisphosphonates
. Local staging with a positron emission tomography (PET) scan

Correct Answer & Explanation

. Pre-operative angiogram and selective embolization

Explanation

Metastatic bone lesions from renal cell carcinoma and thyroid carcinoma are highly vascular. Pre-operative embolization is critical to significantly reduce the risk of massive, life-threatening intra-operative hemorrhage.

Question 4887

Topic: 10. Pathology and Oncology

A 16-year-old girl is diagnosed with a high-grade intramedullary osteosarcoma of the distal femur. Her family history is significant for a mother with early-onset breast cancer and a sibling with an adrenocortical carcinoma. A germline mutation in which of the following genes is most likely responsible for her condition?

. RB1
. TP53
. EXT1
. NF1
. APC

Correct Answer & Explanation

. TP53

Explanation

The clinical picture describes Li-Fraumeni syndrome, an autosomal dominant disorder caused by a germline mutation in the TP53 tumor suppressor gene. It carries a markedly increased risk of developing osteosarcoma, breast cancer, leukemia, and soft tissue sarcomas.

Question 4888

Topic: 10. Pathology and Oncology

A 34-year-old male presents with a slow-growing, deep-seated soft tissue mass in the plantar aspect of his foot. Radiographs demonstrate stippled calcifications within the soft tissues. Biopsy confirms a malignant spindle cell neoplasm. Which of the following translocations is diagnostic for this tumor?

. t(11;22)(q24;q12)
. t(X;18)(p11;q11)
. t(12;16)(q13;p11)
. t(2;13)(q35;q14)
. t(9;22)(q34;q11)

Correct Answer & Explanation

. t(X;18)(p11;q11)

Explanation

Synovial sarcoma frequently presents in young adults in the extremities, especially the foot and ankle, and often shows intralesional calcifications on radiographs. It is genetically characterized by the t(X;18)(p11;q11) translocation, which fuses the SYT and SSX genes.

Question 4889

Topic: 10. Pathology and Oncology

A 22-year-old female presents with multiple painless, hard masses on her hands. Examination reveals multiple soft tissue hemangiomas with phleboliths on her forearm and trunk. Radiographs of the hands show multiple expansile lytic lesions with rings-and-arcs calcifications in the phalanges. What is the patient's lifetime risk of malignant transformation of her bone lesions?

. Less than 1%
. 5%
. 10-20%
. 30-40%
. Approaching 100%

Correct Answer & Explanation

. Approaching 100%

Explanation

The patient has Maffucci syndrome, characterized by multiple enchondromas and soft tissue hemangiomas. The lifetime risk of malignant transformation to chondrosarcoma or developing visceral malignancies is extremely high, often cited as approaching 100%.

Question 4890

Topic: 10. Pathology and Oncology

A 28-year-old male presents with chronic anterior shin pain. Radiographs reveal an eccentric, multi-locular, lytic lesion in the anterior tibial diaphysis with a soap-bubble appearance. Biopsy shows nests of cells with a biphasic pattern consisting of epithelial cells and osteofibrous stroma. Immunohistochemistry will most likely be positive for which of the following markers?

. S-100
. Brachyury
. Cytokeratin
. CD99
. CD34

Correct Answer & Explanation

. Cytokeratin

Explanation

Adamantinoma is a rare, low-grade malignant bone tumor with a strong predilection for the anterior tibial diaphysis. It is characterized by epithelial differentiation, making it reliably positive for epithelial markers such as cytokeratin and EMA.

Question 4891

Topic: 10. Pathology and Oncology

A 15-year-old boy presents with right shoulder pain. Radiographs show a well-circumscribed lytic lesion in the proximal humeral epiphysis with a thin sclerotic margin. Histology reveals polyhedral cells with grooved nuclei and areas of pericellular chicken-wire calcification. Which gene is most commonly mutated in this tumor?

. GNAS
. H3F3A
. H3F3B
. IDH1
. EXT1

Correct Answer & Explanation

. H3F3B

Explanation

Chondroblastoma is a benign epiphyseal cartilage tumor uniquely characterized by chicken-wire calcifications. It is primarily driven by mutations in the H3F3B gene, distinguishing it from giant cell tumors which have H3F3A mutations.

Question 4892

Topic: 10. Pathology and Oncology

A 28-year-old female presents with a painless mass behind her knee. Radiographs reveal a dense, heavily ossified mass arising from the posterior cortex of the distal femur. There is no medullary involvement. Molecular analysis of the biopsy specimen is most likely to show amplification of which of the following?

. MDM2 and CDK4
. MYC and ERG
. HER2 and NEU
. EWSR1 and FLI1
. BRAF and KRAS

Correct Answer & Explanation

. MDM2 and CDK4

Explanation

Parosteal osteosarcoma is a low-grade surface osteosarcoma typically found on the posterior aspect of the distal femur. Genetically, it is characterized by supernumerary ring chromosomes leading to the amplification of the MDM2 and CDK4 genes.

Question 4893

Topic: 10. Pathology and Oncology

A 45-year-old male is diagnosed with a myxoid liposarcoma of the deep posterior thigh. Genetic testing confirms a t(12;16) translocation. When staging this patient, in addition to standard chest imaging, what other imaging modality is critical due to this tumor's unique pattern of spread?

. MRI of the brain
. MRI of the total spine and pelvis
. Ultrasound of regional lymph nodes
. Upper gastrointestinal endoscopy
. Bone marrow aspiration and biopsy

Correct Answer & Explanation

. MRI of the total spine and pelvis

Explanation

Myxoid liposarcoma has a strong propensity to metastasize to extrapulmonary sites, particularly bone and the spine. Therefore, staging should include an MRI of the total spine and pelvis to detect these skip bone metastases.

Question 4894

Topic: 10. Pathology and Oncology

A 40-year-old woman complains of burning pain in her forefoot that radiates into her toes, feeling 'like walking on a marble'. A Mulder's click is elicited on examination. If surgical excision of the underlying pathology is performed, histological evaluation of the specimen would most likely show:

. True axonal proliferation forming a discrete benign neoplastic tumor
. Malignant peripheral nerve sheath tumor characteristics
. Perineural fibrosis, local vascular proliferation, and axonal degeneration
. Granulomatous inflammation with multinucleated giant cells
. Amyloid deposition within the nerve fascicles

Correct Answer & Explanation

. Perineural fibrosis, local vascular proliferation, and axonal degeneration

Explanation

The clinical presentation describes a Morton's neuroma, most commonly located in the third intermetatarsal space. Histologically, a Morton's neuroma is not a true neoplasm (neuroma) but rather a compressive neuropathy characterized by perineural fibrosis, local vascular proliferation, demyelination, and axonal degeneration.

Question 4895

Topic: 10. Pathology and Oncology

A 65-year-old female presents with bilateral, painless clunking of her scapulae with shoulder movement. MRI reveals bilateral, ill-circumscribed soft tissue masses deep to the inferior angle of the scapula with signal intensity similar to skeletal muscle interspersed with fat. What is the most likely diagnosis?

. Lipoma
. Sarcoma
. Elastofibroma dorsi
. Osteochondroma of the scapula
. Desmoid tumor

Correct Answer & Explanation

. Elastofibroma dorsi

Explanation

Elastofibroma dorsi is a benign, slow-growing soft-tissue pseudotumor characteristically located at the inferior pole of the scapula, deep to the serratus anterior and latissimus dorsi. It is often bilateral (up to 30%) and occurs in older individuals. The MRI appearance of muscle-like fibrous tissue interspersed with streaks of fat is highly characteristic.

Question 4896

Topic: 10. Pathology and Oncology

A 35-year-old male presents with a painful mass in the distal femur. Biopsy reveals an osteochondroma with secondary aneurysmal bone cyst formation. MRI shows the lesion contained entirely within the cortical bone, with no evidence of soft tissue extension. Which Enneking stage best describes this tumor?

. Stage 1 (Latent)
. Stage 2 (Active)
. Stage 3 (Aggressive)
. Stage IA
. Stage IB

Correct Answer & Explanation

. Stage 2 (Active)

Explanation

The Enneking staging system for benign tumors classifies them into Latent (Stage 1), Active (Stage 2), and Aggressive (Stage 3). A symptomatic lesion expanding within the bone, even with secondary changes like aneurysmal bone cyst formation, is considered Active (Stage 2) as it's not latent and not yet breaking out of its compartment or causing significant local destruction beyond expansion, which would be Stage 3. Osteochondroma itself is typically latent, but secondary ABC or pain makes it active.

Question 4897

Topic: 10. Pathology and Oncology
A 60-year-old female presents with a slowly enlarging mass in her thigh. Biopsy confirms a low-grade myxofibrosarcoma. MRI shows the tumor is confined within the anterior fascial compartment of the thigh, with no evidence of neurovascular involvement or extension beyond the fascial boundaries. No regional nodal or distant metastases are identified. What is the appropriate Enneking surgical stage for this tumor?
. Stage IA
. Stage IB
. Stage IIA
. Stage IIB
. Stage III

Correct Answer & Explanation

. Stage IA

Explanation

The Enneking Musculoskeletal Tumor Society (MSTS) staging system for malignant tumors uses a combination of histological grade (G), local extent (T), and presence of metastasis (M). Stage I tumors are low-grade (G1). Stage A indicates intracompartmental (T1), while Stage B indicates extracompartmental (T2). This patient has a low-grade (G1) myxofibrosarcoma confined within the anterior fascial compartment (T1), thus classifying it as Stage IA.

Question 4898

Topic: 10. Pathology and Oncology
A 16-year-old male presents with a rapidly growing, painful mass in his proximal tibia. Biopsy confirms high-grade osteosarcoma. MRI demonstrates cortical breach with extensive soft tissue involvement extending beyond the fascial compartment, encasing the popliteal artery. CT chest is negative for metastasis. What is the Enneking surgical stage?
. Stage IA
. Stage IB
. Stage IIA
. Stage IIB
. Stage III

Correct Answer & Explanation

. Stage IIB

Explanation

High-grade malignant tumors are classified as Stage II (G2). Stage A indicates intracompartmental (T1), and Stage B indicates extracompartmental (T2). In this case, the osteosarcoma is high-grade (G2) and has extended beyond the fascial compartment, encasing vital neurovascular structures, making it extracompartmental (T2). With no distant metastasis, this corresponds to Stage IIB.

Question 4899

Topic: 10. Pathology and Oncology
A 55-year-old male presents with a large, painful shoulder mass. Biopsy reveals a high-grade undifferentiated pleomorphic sarcoma. PET-CT shows FDG avidity in the shoulder mass and a single lung nodule, confirmed as metastatic disease on biopsy. What is the Enneking surgical stage?
. Stage IA
. Stage IIB
. Stage III (T1)
. Stage III (T2)
. Stage III (M)

Correct Answer & Explanation

. Stage III (M)

Explanation

According to the Enneking MSTS staging system, any malignant tumor, regardless of its histological grade (G) or local extent (T), that has distant metastasis (M1) is automatically classified as Stage III. The presence of metastatic lung disease dictates this classification.

Question 4900

Topic: 10. Pathology and Oncology

Which of the following best defines an intracompartmental tumor in the Enneking staging system?

. A tumor confined to the bone cortex.
. A tumor completely surrounded by a reactive pseudocapsule.
. A tumor confined within an anatomical space or bone with a natural barrier to extension.
. A tumor that does not invade neurovascular structures.
. A tumor less than 5 cm in greatest dimension.

Correct Answer & Explanation

. A tumor confined within an anatomical space or bone with a natural barrier to extension.

Explanation

In the Enneking system, an intracompartmental (T1) tumor is one confined within an anatomical compartment, which can be an intraosseous compartment, an articular compartment, or a well-defined soft tissue fascial compartment. This anatomical barrier prevents easy spread. A reactive pseudocapsule can exist in both intracompartmental and extracompartmental tumors, and size is not the primary determinant. Neurovascular invasion often implies extracompartmental extension, but the definition hinges on the anatomical boundaries.

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