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10. Pathology and Oncology MCQs

Practice Set 238 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 4741

Topic: 10. Pathology and Oncology

A 35-year-old male presents with a painless, eccentric, expansile 'soap-bubble' lytic lesion in the anterior diaphyseal cortex of the tibia. A biopsy reveals islands of epithelial cells within a benign-appearing fibrous stroma. What is the most appropriate surgical management for this patient?

. Intralesional curettage and bone grafting
. Intralesional curettage, high-speed burring, and polymethylmethacrylate cementation
. Wide en bloc resection with margin-negative excision
. Radiation therapy alone
. Neoadjuvant chemotherapy followed by curettage

Correct Answer & Explanation

. Wide en bloc resection with margin-negative excision

Explanation

The diagnosis is adamantinoma, a rare, low-grade malignant bone tumor that almost exclusively occurs in the anterior diaphyseal cortex of the tibia. Histologically, it is biphasic with epithelial cells in a fibrous stroma. Because it is a low-grade malignancy with a high rate of local recurrence and potential for metastasis, the standard of care is wide en bloc resection. Curettage results in unacceptably high recurrence rates.

Question 4742

Topic: 10. Pathology and Oncology

A 16-year-old boy presents with knee pain. Radiographs demonstrate an eccentric, expansile, purely lytic lesion in the distal femur metaphysis. MRI shows multiple fluid-fluid levels. Genetic analysis of the tissue is most likely to show a rearrangement involving which of the following genes?

. USP6
. GNAS
. H3F3A
. EXT1
. MDM2

Correct Answer & Explanation

. USP6

Explanation

The lesion described is an aneurysmal bone cyst (ABC), characterized by eccentric, expansile lytic lesions with fluid-fluid levels on MRI. Primary ABCs are now known to be true neoplasms, characterized by a recurrent t(16;17) translocation that results in the upregulation of the USP6 gene (ubiquitin-specific protease 6). GNAS is seen in fibrous dysplasia, H3F3A in giant cell tumor, EXT1 in multiple hereditary exostoses, and MDM2 in parosteal osteosarcoma.

Question 4743

Topic: 10. Pathology and Oncology

A 55-year-old female with a history of breast cancer presents with right thigh pain. Radiographs show a lytic metastatic lesion in the peritrochanteric region of the femur. The lesion involves approximately 50% of the cortical diameter. She describes her pain as moderate with weight-bearing. Using Mirels' criteria, what is her score and recommended management?

. Score 7; local radiation therapy only
. Score 8; prophylactic internal fixation is highly recommended
. Score 9; prophylactic internal fixation is highly recommended
. Score 10; prophylactic internal fixation is highly recommended
. Score 11; amputation is recommended

Correct Answer & Explanation

. Score 10; prophylactic internal fixation is highly recommended

Explanation

Mirels' criteria assess the risk of pathologic fracture. Variables are scored 1-3: Site (Upper limb=1, Lower limb=2, Peritrochanteric=3), Size (<1/3=1, 1/3-2/3=2, >2/3=3), Nature (Blastic=1, Mixed=2, Lytic=3), Pain (Mild=1, Moderate=2, Functional=3). Score: Peritrochanteric (3) + 50% diameter (2) + Lytic (3) + Moderate pain (2) = 10. A score of 9 or greater carries a high fracture risk, and prophylactic fixation is recommended.

Question 4744

Topic: 10. Pathology and Oncology

A 32-year-old male with a history of total colectomy for familial adenomatous polyposis (FAP) presents with a deep, firm mass in his posterior thigh. Biopsy shows a proliferation of uniform spindle cells in a dense collagenous background, with absent mitotic activity. Which of the following proteins is most likely to show aberrant nuclear accumulation on immunohistochemistry?

. p53
. Beta-catenin
. S100
. CD99
. Cytokeratin

Correct Answer & Explanation

. Beta-catenin

Explanation

The patient has a deep fibromatosis (desmoid tumor), strongly associated with Gardner syndrome (caused by APC gene mutations). Both sporadic and syndromic desmoid tumors result in the dysregulation of the Wnt/beta-catenin signaling pathway. The hallmark immunohistochemical finding is aberrant nuclear accumulation of beta-catenin.

Question 4745

Topic: 10. Pathology and Oncology

A 55-year-old male presents with chronic constipation, urinary hesitancy, and vague sacral pain. MRI shows a large, destructive, midline lobulated mass in the sacrum. Biopsy reveals large cells with prominent intracytoplasmic vacuoles arranged in cords. Which immunohistochemical marker is highly specific for the diagnosis of this tumor?

. Brachyury
. CD34
. Desmin
. MyoD1
. SMA (Smooth Muscle Actin)

Correct Answer & Explanation

. Brachyury

Explanation

The clinical and histologic description is classic for chordoma, a slow-growing malignant tumor arising from notochord remnants. Histologically, it features 'physaliferous' cells (large cells with bubbly, vacuolated cytoplasm). Brachyury, a transcription factor essential for notochord development, is highly specific for chordoma.

Question 4746

Topic: 10. Pathology and Oncology

A 40-year-old male presents with shoulder pain. Radiographs demonstrate an expansile, radiolucent lesion in the epiphysis of the proximal humerus with focal calcifications. A biopsy is read as showing 'chondroblastic cells, multinucleated giant cells, and areas of hyaline cartilage.' Given the patient's age and location, what is the most likely diagnosis, and what is the required treatment?

. Chondroblastoma; treated with intralesional curettage
. Clear cell chondrosarcoma; treated with wide en bloc resection
. Chondromyxoid fibroma; treated with wide en bloc resection
. Enchondroma; treated with observation
. Giant cell tumor of bone; treated with denosumab

Correct Answer & Explanation

. Clear cell chondrosarcoma; treated with wide en bloc resection

Explanation

While chondroblastoma presents as an epiphyseal lytic lesion with giant cells and chondroblasts, it typically occurs in skeletally immature patients (teens). In an adult (e.g., 40-year-old) with a similar epiphyseal lesion, clear cell chondrosarcoma must be strongly suspected. It is a low-grade malignancy that requires wide en bloc resection to prevent local recurrence and metastasis.

Question 4747

Topic: 10. Pathology and Oncology
A 58-year-old female presents with a rapidly growing, painful mass in her left scapula. She underwent a lumpectomy and local radiation therapy for left breast cancer 15 years ago. Biopsy of the scapular mass reveals a high-grade, pleomorphic spindle cell sarcoma producing osteoid. According to Cahan's criteria for radiation-induced sarcoma, all of the following must be met EXCEPT:
. The sarcoma must arise within the prior field of radiation
. There must be a latency period of at least 15 years
. The sarcoma must be histologically confirmed
. The histology must differ from the primary tumor
. The original lesion treated with radiation must have been non-malignant or a different malignancy

Correct Answer & Explanation

. There must be a latency period of at least 15 years

Explanation

Cahan's criteria define a radiation-induced sarcoma: 1) The sarcoma must arise in the area previously irradiated; 2) The patient must have had a latency period, which is typically greater than 3-5 years (but not strictly 15 years); 3) Histologic proof of the sarcoma; 4) The sarcoma must be histologically distinct from the primary tumor. Osteosarcoma and UPS are the most common radiation-induced sarcomas.

Question 4748

Topic: Bone Tumors

An 18-year-old male presents with a painful swelling over the anterior tibia. Radiographs show a radiolucent surface lesion in the diaphysis with crater-like scalloping of the underlying cortex and perpendicular bone spicules ('hair-on-end'). MRI confirms no medullary involvement. Histology shows predominantly intermediate-grade chondroblastic matrix. What is the diagnosis?

. Parosteal osteosarcoma
. Periosteal osteosarcoma
. High-grade surface osteosarcoma
. Periosteal chondroma
. Osteochondroma

Correct Answer & Explanation

. Periosteal osteosarcoma

Explanation

Periosteal osteosarcoma is a rare, intermediate-grade surface osteosarcoma that typically arises on the diaphysis of long bones. Radiographically, it causes a scalloped saucerization of the outer cortex with perpendicular spicules of bone. Histologically, it is predominantly chondroblastic. Parosteal osteosarcoma is low-grade, heavily ossified, fibroblastic, and typically posterior distal femur.

Question 4749

Topic: 10. Pathology and Oncology

A 24-year-old male presents with a 6-month history of a dull, aching back pain that is not completely relieved by NSAIDs. CT scan reveals a 3.5 cm expansile, lytic lesion with scattered central calcifications in the posterior elements of L4. Biopsy shows prominent osteoblastic rimming of osteoid trabeculae within a highly vascular connective tissue stroma. What is the most common secondary change or complication associated with this lesion?

. Malignant transformation into osteosarcoma
. Development of an aneurysmal bone cyst (ABC)
. Spontaneous regression after skeletal maturity
. Pulmonary metastasis
. Transformation into a giant cell tumor

Correct Answer & Explanation

. Development of an aneurysmal bone cyst (ABC)

Explanation

The lesion described is an osteoblastoma (>2 cm, posterior elements of spine, histologically identical to osteoid osteoma but larger and less responsive to NSAIDs). Osteoblastomas have a high tendency to undergo secondary changes, most notably the development of a secondary aneurysmal bone cyst (ABC) in up to 10-15% of cases.

Question 4750

Topic: 10. Pathology and Oncology
A 45-year-old female undergoes a wide resection of a 7 cm deep soft tissue mass in the vastus medialis. Pathology confirms a high-grade undifferentiated pleomorphic sarcoma. MRI and intraoperative findings confirm the tumor was strictly confined within the deep fascia of the anterior compartment of the thigh, without bony or neurovascular involvement. A staging PET-CT shows no regional or distant metastases. What is the Enneking Surgical Stage for this patient?
. Stage IA
. Stage IB
. Stage IIA
. Stage IIB
. Stage III

Correct Answer & Explanation

. Stage IIA

Explanation

The Enneking staging system relies on Grade (G1=Low, G2=High), Site (T1=Intracompartmental, T2=Extracompartmental), and Metastasis (M0=None, M1=Mets). This tumor is high-grade (G2), which places it in Stage II. It is confined within the compartment (T1), making it IIA. There are no metastases (M0).

Question 4751

Topic: 10. Pathology and Oncology

A 42-year-old male is diagnosed with a large, deep myxoid liposarcoma of the posterior thigh. Genetic testing confirms the characteristic t(12;16) FUS-DDIT3 translocation. During the staging workup, the oncologist recommends a whole-body MRI rather than relying solely on a chest CT. This recommendation is based on the unique propensity of myxoid liposarcoma to metastasize to which of the following locations?

. Liver
. Brain
. Lymph nodes
. Extrapulmonary soft tissues and bone/spine
. Contralateral extremity

Correct Answer & Explanation

. Extrapulmonary soft tissues and bone/spine

Explanation

Myxoid liposarcoma has a unique metastatic pattern. While most soft tissue sarcomas metastasize primarily to the lungs, myxoid liposarcoma frequently metastasizes to extrapulmonary sites, particularly other soft tissues, the retroperitoneum, and bone/spine, often before pulmonary involvement. Therefore, whole-body MRI or spine MRI is required for staging.

Question 4752

Topic: 10. Pathology and Oncology

A 25-year-old male presents with a slow-growing, deep-seated soft tissue mass around the knee. Radiographs reveal focal stippled calcifications within the soft tissue mass. Core needle biopsy demonstrates a biphasic tumor consisting of both epithelial elements arranged in glandular structures and a spindle cell component. What is the defining chromosomal translocation associated with this malignancy?

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

Correct Answer & Explanation

. t(X;18)

Explanation

The clinical and histological presentation describes a synovial sarcoma, which frequently presents near joints in young adults and often contains focal calcifications (in about 30% of cases). The classic genetic hallmark is the t(X;18)(p11;q11) translocation, resulting in the SYT-SSX fusion gene. t(11;22) is seen in Ewing sarcoma; t(12;16) in myxoid liposarcoma; t(2;13) in alveolar rhabdomyosarcoma; and t(9;22) in extraskeletal myxoid chondrosarcoma (and CML).

Question 4753

Topic: 10. Pathology and Oncology

A 60-year-old female with a history of breast cancer presents with a mixed lytic and blastic lesion in the peritrochanteric region of the right femur. The lesion involves 2/3 of the cortical diameter. She reports moderate pain with ambulation. According to Mirels' criteria, what is the patient's calculated score and the most appropriate orthopedic management?

. Score 7; Observation and bisphosphonates
. Score 8; External beam radiation therapy alone
. Score 9; Prophylactic internal fixation
. Score 10; Wide en bloc resection and endoprosthetic reconstruction
. Score 11; Preoperative embolization followed by intralesional curettage

Correct Answer & Explanation

. Score 9; Prophylactic internal fixation

Explanation

Mirels' criteria are used to determine the risk of impending pathologic fracture. The criteria assess four categories (Site, Pain, Lesion type, Size) with points from 1 to 3. Site: Peritrochanteric (lower limb) = 2. Pain: Moderate = 2. Lesion: Mixed = 2. Size: 2/3 (>1/3 to 2/3) = 3. Total score = 2 + 2 + 2 + 3 = 9. A score of 9 or greater carries a high risk of fracture (>=33%) and is an indication for prophylactic internal fixation.

Question 4754

Topic: 10. Pathology and Oncology

A 65-year-old male is scheduled for a wide resection and intercalary reconstruction of a destructive lytic lesion in the humeral diaphysis. His medical history is significant for a prior nephrectomy for renal cell carcinoma. Which preoperative intervention is most critical to minimize intraoperative morbidity?

. Administration of neoadjuvant methotrexate
. Preoperative external beam radiation therapy
. Angiography and selective arterial embolization
. Intravenous administration of denosumab
. Placement of a prophylactic inferior vena cava filter

Correct Answer & Explanation

. Angiography and selective arterial embolization

Explanation

Metastatic lesions from renal cell carcinoma (RCC) and thyroid carcinoma are notoriously hypervascular. Preoperative selective angiography and embolization performed 24-48 hours before surgery are critical to minimize catastrophic intraoperative blood loss. Neoadjuvant radiation or chemotherapy are not standard immediate preoperative modalities for metastatic RCC in this context.

Question 4755

Topic: 10. Pathology and Oncology

A 45-year-old female presents with a destructive bone lesion in her left scapula. Fifteen years ago, she underwent lumpectomy and adjuvant radiation therapy for breast cancer. Biopsy of the scapular lesion reveals high-grade pleomorphic spindle cells producing osteoid. According to Cahan's criteria, which of the following is essential to establish a diagnosis of radiation-induced sarcoma?

. The new tumor must develop within 2 years of the radiation exposure
. The histology of the new tumor must be identical to the primary tumor
. The new tumor must arise within the prior radiation field
. The patient must possess a documented BRCA1 or BRCA2 mutation
. The tumor must demonstrate a substantial response to neoadjuvant chemotherapy

Correct Answer & Explanation

. The new tumor must arise within the prior radiation field

Explanation

Cahan's criteria for radiation-induced sarcoma include: 1) The sarcoma must arise within the previously irradiated field; 2) A latent period must exist (typically >4 years, average 10-15 years); 3) The histology must be distinct from the primary tumor; 4) There must be histological proof of a sarcoma. Therefore, the tumor arising strictly within the prior radiation field is an essential criterion.

Question 4756

Topic: 10. Pathology and Oncology

A 40-year-old male presents with a painless, deep intramuscular mass in the posterior thigh. MRI reveals a lesion with intermediate signal on T1 and marked hyperintensity on T2. Biopsy demonstrates a prominent plexiform capillary network and lipoblasts within a myxoid stroma. What is the expected chromosomal translocation for this tumor?

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

Correct Answer & Explanation

. t(12;16)

Explanation

The diagnosis is myxoid liposarcoma, characterized histologically by a myxoid background, 'crow's feet' or plexiform capillary network, and lipoblasts. The characteristic genetic alteration is the t(12;16)(q13;p11) translocation, resulting in the FUS-DDIT3 (or FUS-CHOP) fusion transcript. These tumors are uniquely sensitive to radiation therapy.

Question 4757

Topic: 10. Pathology and Oncology

A 5-year-old boy presents with anterior bowing of the tibia. Radiographs show an eccentric, multi-loculated lytic lesion in the anterior cortex of the tibial diaphysis. Biopsy reveals a fibrous stroma containing trabeculae of woven bone with prominent osteoblastic rimming. Immunohistochemical staining for cytokeratin is negative. What is the most appropriate initial management?

. Immediate wide en bloc resection and vascularized fibular graft
. Observation and bracing to prevent deformity/fracture until skeletal maturity
. Intralesional curettage and bone grafting with allograft
. Neoadjuvant chemotherapy followed by limb salvage surgery
. External beam radiation therapy

Correct Answer & Explanation

. Observation and bracing to prevent deformity/fracture until skeletal maturity

Explanation

The clinical, radiographic, and histological picture describes osteofibrous dysplasia (Campanacci disease). It occurs almost exclusively in the anterior tibia in young children (unlike fibrous dysplasia, the woven bone here HAS prominent osteoblastic rimming, and cytokeratin is negative, ruling out adamantinoma). Management is primarily observation and bracing (watchful waiting) because the lesion often stabilizes or regresses after skeletal maturity, and early surgery carries a high risk of recurrence.

Question 4758

Topic: 10. Pathology and Oncology

A 55-year-old female presents with diffuse bone pain. Radiographs reveal multiple expansile, lytic lesions in the pelvis and bilateral femurs. Biopsy of a pelvic lesion demonstrates clusters of multinucleated giant cells embedded in a highly vascularized, hemorrhagic fibrous stroma. Routine laboratory workup reveals significantly elevated serum calcium and alkaline phosphatase. Which additional test is most likely to confirm the underlying etiology?

. Serum protein electrophoresis (SPEP)
. Intact parathyroid hormone (PTH) level
. Thyroid stimulating hormone (TSH)
. 1,25-dihydroxyvitamin D level
. Prostate-specific antigen (PSA)

Correct Answer & Explanation

. Intact parathyroid hormone (PTH) level

Explanation

The presence of multiple lytic lesions with histology showing multinucleated giant cells in a hemorrhagic stroma ('brown tumor'), accompanied by hypercalcemia and elevated alkaline phosphatase, strongly suggests hyperparathyroidism. Confirming the etiology requires checking the intact parathyroid hormone (PTH) level. Brown tumors are not true neoplasms but rather a reactive cellular process due to intense osteoclastic bone resorption.

Question 4759

Topic: Bone Tumors

An 18-year-old male is undergoing treatment with the MAP protocol (High-dose Methotrexate, Adriamycin/Doxorubicin, and Cisplatin) for high-grade conventional osteosarcoma of the distal femur. Six months into treatment, he presents with progressive dyspnea on exertion, orthopnea, and lower extremity edema. Echocardiography reveals a significantly reduced left ventricular ejection fraction. Which chemotherapeutic agent is most likely responsible?

. Methotrexate
. Cisplatin
. Doxorubicin
. Ifosfamide
. Bleomycin

Correct Answer & Explanation

. Doxorubicin

Explanation

Doxorubicin (Adriamycin) is an anthracycline known for causing dose-dependent, cumulative, and potentially irreversible cardiotoxicity (cardiomyopathy leading to congestive heart failure). Cisplatin is associated with ototoxicity and nephrotoxicity. Methotrexate is associated with hepatotoxicity, mucositis, and myelosuppression. Ifosfamide is known for hemorrhagic cystitis. Bleomycin is associated with pulmonary fibrosis.

Question 4760

Topic: 10. Pathology and Oncology

A 22-year-old male presents with mild proximal tibial pain. Radiographs show an eccentric, lytic metaphyseal lesion with a well-defined sclerotic margin, lacking internal calcification. Histology reveals a lobulated pattern of myxoid and chondroid tissue. The cells are stellate, and there is distinctly increased cellularity at the periphery of the lobules. What is the most likely diagnosis?

. Chondroblastoma
. Chondromyxoid fibroma
. Giant cell tumor of bone
. Enchondroma
. Non-ossifying fibroma

Correct Answer & Explanation

. Chondromyxoid fibroma

Explanation

Chondromyxoid fibroma (CMF) is a rare benign cartilage tumor typically presenting as an eccentric metaphyseal lesion with a sclerotic rim. Classic histology demonstrates a lobular architecture with myxoid/chondroid stroma and increased cellularity at the lobule peripheries (often with osteoclast-like giant cells). Unlike enchondromas or chondroblastomas, it rarely exhibits internal calcification on imaging.

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