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10. Pathology and Oncology MCQs

Practice Set 237 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 4721

Topic: 10. Pathology and Oncology

A 12-year-old girl is evaluated for a permeative lesion in the diaphysis of the humerus with an associated 'onion-skin' periosteal reaction. A biopsy is performed. Which of the following chromosomal translocations is most characteristic of the suspected diagnosis?

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

Correct Answer & Explanation

. t(11;22)

Explanation

The clinical and radiographic presentation is classic for Ewing sarcoma. The characteristic translocation is t(11;22)(q24;q12), which results in the EWS-FLI1 fusion protein. This occurs in approximately 85% of Ewing sarcoma cases.

Question 4722

Topic: Bone Tumors

A 19-year-old male presents with progressive back pain that is worse at night and poorly relieved by NSAIDs. Imaging reveals a 2.5 cm radiolucent nidus with surrounding sclerosis in the posterior elements of L4. What is the most likely diagnosis?

. Osteoid osteoma
. Osteoblastoma
. Aneurysmal bone cyst
. Osteosarcoma
. Eosinophilic granuloma

Correct Answer & Explanation

. Osteoid osteoma

Explanation

While osteoid osteoma and osteoblastoma are histologically similar, osteoblastomas are distinguished by a nidus size greater than 2 cm (often >1.5-2 cm) and pain that is less responsive to NSAIDs. They commonly occur in the posterior elements of the spine.

Question 4723

Topic: 10. Pathology and Oncology

A 14-year-old boy has an expansile, multiloculated, eccentrically located lytic lesion in the distal femoral metaphysis. MRI demonstrates multiple fluid-fluid levels. What is the most common underlying genetic abnormality associated with a primary form of this lesion?

. USP6 gene rearrangement
. GNAS1 mutation
. EXT1 mutation
. CDKN2A deletion
. MDM2 amplification

Correct Answer & Explanation

. USP6 gene rearrangement

Explanation

Primary Aneurysmal Bone Cysts (ABCs) are true neoplastic processes characterized by translocations involving the USP6 gene on chromosome 17p13. Fluid-fluid levels on MRI are characteristic, though not entirely pathognomonic, for ABCs.

Question 4724

Topic: 10. Pathology and Oncology
In the staging of soft tissue sarcomas according to the Musculoskeletal Tumor Society (Enneking) staging system, which of the following defines a stage IIB tumor?
. Low grade, intracompartmental
. Low grade, extracompartmental
. High grade, intracompartmental
. High grade, extracompartmental
. Any grade, with distant metastasis

Correct Answer & Explanation

. High grade, extracompartmental

Explanation

In the Enneking system for sarcomas: Stage I is low grade, Stage II is high grade, and Stage III indicates metastases. The letter 'A' denotes intracompartmental location, and 'B' denotes extracompartmental. Thus, Stage IIB is a high-grade, extracompartmental lesion.

Question 4725

Topic: 10. Pathology and Oncology

A 28-year-old male presents with a slow-growing mass in his foot. MRI shows a multilobulated mass near the plantar fascia. Biopsy reveals a biphasic tumor with both epithelial and spindle cell components. Which cytogenetic abnormality is diagnostic for this tumor?

. t(X;18)(p11;q11)
. t(12;16)(q13;p11)
. t(2;13)(q35;q14)
. t(9;22)(q22;q12)
. t(11;22)(q24;q12)

Correct Answer & Explanation

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

Explanation

The tumor described is a synovial sarcoma, which frequently presents in the distal extremities of young adults and is characterized histologically by biphasic or monophasic patterns. The diagnostic translocation is t(X;18)(p11;q11), creating the SYT-SSX fusion gene.

Question 4726

Topic: Bone Tumors

A 30-year-old female presents with a painless mass on the posterior aspect of her distal thigh. Radiographs show a dense, heavily ossified mass attached to the posterior cortex of the distal femur with a 'string sign'. What is the most likely diagnosis?

. Periosteal osteosarcoma
. Parosteal osteosarcoma
. Osteochondroma
. High-grade surface osteosarcoma
. Myositis ossificans

Correct Answer & Explanation

. Periosteal osteosarcoma

Explanation

Parosteal osteosarcoma is a low-grade surface osteosarcoma that typically occurs on the posterior aspect of the distal femur. It presents as a heavily ossified mass, often with a radiolucent cleft (string sign) separating it from the underlying cortex.

Question 4727

Topic: 10. Pathology and Oncology

A 65-year-old male presents with a destructive lytic lesion in the proximal humerus. Biopsy is planned. Medical history includes a nephrectomy 5 years ago for renal cell carcinoma. What is a critical pre-operative step before performing an intralesional curettage or stabilization?

. Pre-operative radiation therapy
. Systemic chemotherapy
. Pre-operative embolization
. Bone scan to rule out other lesions
. Administering bisphosphonates intravenously

Correct Answer & Explanation

. Pre-operative radiation therapy

Explanation

Renal cell carcinoma and thyroid carcinoma metastases to bone are notoriously hypervascular. Pre-operative embolization is highly recommended to significantly reduce intraoperative blood loss during biopsy or surgical stabilization.

Question 4728

Topic: Bone Tumors

A 62-year-old man presents with generalized bone pain, fatigue, and renal impairment. Radiographs show multiple 'punched-out' lytic lesions in the skull and pelvis. Which of the following laboratory findings is most specific for confirming the diagnosis?

. Elevated alkaline phosphatase
. Elevated serum prostate-specific antigen
. Monoclonal spike on serum protein electrophoresis
. Positive Philadelphia chromosome
. Elevated serum calcitonin

Correct Answer & Explanation

. Elevated alkaline phosphatase

Explanation

The clinical picture (CRAB criteria: hyperCalcemia, Renal involvement, Anemia, Bone lytic lesions) is classic for Multiple Myeloma. A monoclonal spike (M-protein) on serum or urine protein electrophoresis (SPEP/UPEP) confirms the diagnosis of a plasma cell dyscrasia.

Question 4729

Topic: Bone Tumors

A 25-year-old female presents with a painless bowing deformity of her proximal femur. Radiographs reveal a ground-glass intramedullary lesion with cortical thinning and a 'shepherd's crook' deformity. The underlying pathophysiology involves a mutation in which of the following?

. Gs alpha protein (GNAS1)
. Fibroblast growth factor receptor 3 (FGFR3)
. Retinoblastoma gene (RB1)
. EXT1 gene
. Tumor suppressor p53

Correct Answer & Explanation

. Gs alpha protein (GNAS1)

Explanation

The presentation is consistent with fibrous dysplasia, characterized by the 'ground-glass' appearance and bowing deformities (shepherd's crook in the proximal femur). The etiology is a somatic activating mutation in the GNAS1 gene, which encodes the alpha subunit of the stimulatory G protein.

Question 4730

Topic: 10. Pathology and Oncology

A 35-year-old male presents with an indolent, progressive swelling over the anterior shin. Radiographs show a multilobular, eccentric, diaphyseal lytic lesion in the anterior cortex of the tibia. Histopathology shows islands of epithelial cells in a fibrous stroma. What is the most appropriate definitive management?

. Intralesional curettage and bone grafting
. Wide surgical resection
. Radiation therapy
. Chemotherapy followed by curettage
. Amputation

Correct Answer & Explanation

. Intralesional curettage and bone grafting

Explanation

The lesion is an adamantinoma, a rare low-grade malignant bone tumor that almost exclusively occurs in the anterior diaphyseal cortex of the tibia. Because it is a low-grade malignancy that is relatively resistant to radiation and chemotherapy, wide surgical resection with negative margins is the required definitive treatment.

Question 4731

Topic: 10. Pathology and Oncology

A 40-year-old male with a history of Neurofibromatosis Type 1 (NF1) notices rapid enlargement and pain in a pre-existing plexiform neurofibroma in his thigh. Which of the following is the most likely diagnosis?

. Schwannoma
. Malignant peripheral nerve sheath tumor
. Fibrosarcoma
. Synovial sarcoma
. Liposarcoma

Correct Answer & Explanation

. Schwannoma

Explanation

Patients with NF1 have a 5-10% lifetime risk of developing a Malignant Peripheral Nerve Sheath Tumor (MPNST). Rapid enlargement, new-onset pain, or neurological deficit in a previously stable plexiform neurofibroma is highly suspicious for malignant transformation to an MPNST.

Question 4732

Topic: 10. Pathology and Oncology

A 14-year-old girl has a hard, painless mass on her proximal medial tibia. Radiographs show a sessile, bony prominence pointing away from the joint line with medullary continuity between the lesion and the native bone. What is the approximate risk of malignant transformation for this solitary lesion?

. < 1%
. 5%
. 10%
. 25%
. 50%

Correct Answer & Explanation

. < 1%

Explanation

The lesion is a solitary osteochondroma. The risk of malignant transformation (typically to secondary chondrosarcoma) in a solitary osteochondroma is very low, estimated to be less than 1%. In contrast, patients with Multiple Hereditary Exostoses (MHE) have a higher risk (approximately 5-10%).

Question 4733

Topic: 10. Pathology and Oncology

A 45-year-old male presents with a deep, painless mass in his posterior thigh. Biopsy confirms myxoid liposarcoma. This specific soft tissue sarcoma is known for a unique pattern of metastasis compared to other soft tissue sarcomas. Where is it most likely to metastasize besides the lungs?

. Lymph nodes
. Brain
. Other soft tissues and bone
. Liver
. Skin

Correct Answer & Explanation

. Lymph nodes

Explanation

While most soft tissue sarcomas metastasize primarily to the lungs, myxoid liposarcoma has a unique propensity to metastasize to extrapulmonary sites, particularly the spine (bone) and other soft tissue locations. A whole-spine MRI is often part of the staging process.

Question 4734

Topic: 10. Pathology and Oncology

A 30-year-old female complains of recurrent knee effusions and mechanical catching. Aspiration yields dark, blood-tinged synovial fluid. MRI reveals a nodular synovial mass with low signal intensity on both T1 and T2 weighted images, exhibiting blooming artifact on gradient-echo sequences. What is the pathological hallmark causing these MRI findings?

. Dystrophic calcification
. Hemosiderin deposition
. Amyloid accumulation
. Urate crystals
. Cholesterol clefts

Correct Answer & Explanation

. Dystrophic calcification

Explanation

The clinical and MRI findings are classic for Pigmented Villonodular Synovitis (PVNS), also known as Tenosynovial Giant Cell Tumor. The low signal on T1/T2 and blooming artifact on gradient-echo MRI are caused by extensive hemosiderin deposition within the synovial proliferating tissue.

Question 4735

Topic: 10. Pathology and Oncology

A 45-year-old male presents with a deep soft tissue mass in the anterior thigh. A core needle biopsy is planned. Which of the following principles is strictly recommended during the biopsy of a suspected soft tissue sarcoma?

. Transverse incisions should be used to follow Langer's lines for a better cosmetic outcome
. The biopsy tract should cross multiple compartments to ensure a safe margin
. A tourniquet should be applied and the limb exsanguinated with an Esmarch bandage prior to biopsy
. Strict hemostasis is required and the biopsy tract must be excisable during definitive resection
. A drain should be placed exiting through a separate compartment to avoid contaminating the primary incision

Correct Answer & Explanation

. Transverse incisions should be used to follow Langer's lines for a better cosmetic outcome

Explanation

In orthopedic oncology, biopsies must be carefully planned. Longitudinal incisions are mandatory so the tract can be excised en bloc with the tumor during definitive surgery. Strict hemostasis prevents hematoma spread of tumor cells. If a tourniquet is used, the limb should be elevated, NOT exsanguinated with an Esmarch bandage, to avoid pushing tumor cells systemically. Drains should exit in line with the incision, close to it, to allow block excision. Tracts must not contaminate new compartments.

Question 4736

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 attached to the posterior cortex of the distal femur by a broad base, with no medullary involvement. Which of the following molecular abnormalities is most characteristic of this lesion?

. t(11;22) translocation
. MDM2 and CDK4 amplification
. H3F3A mutation
. GNAS mutation
. t(X;18) translocation

Correct Answer & Explanation

. t(11;22) translocation

Explanation

The clinical and radiographic presentation is classic for parosteal osteosarcoma, a low-grade surface osteosarcoma typically found on the posterior distal femur. The hallmark molecular finding is the amplification of MDM2 and CDK4 on chromosome 12q13-15. t(11;22) is Ewing sarcoma; H3F3A is giant cell tumor; GNAS is fibrous dysplasia; t(X;18) is synovial sarcoma.

Question 4737

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a painful, swollen mid-thigh mass. Radiographs show a permeative diaphyseal lytic lesion with an 'onion-skin' periosteal reaction. Biopsy reveals sheets of small round blue cells that stain positive for CD99. The most common translocation associated with this tumor results in a fusion protein that functions as a:

. Tyrosine kinase receptor
. Transcription factor
. Transmembrane ion channel
. Cell-cycle inhibitor
. Matrix metalloproteinase

Correct Answer & Explanation

. Tyrosine kinase receptor

Explanation

Ewing sarcoma is characterized by the t(11;22)(q24;q12) translocation in 85% of cases, fusing the EWS gene to the FLI1 gene. The resultant EWS-FLI1 fusion protein acts as an aberrant transcription factor, leading to unregulated cell growth and proliferation.

Question 4738

Topic: 10. Pathology and Oncology

A 62-year-old male with a known long-standing asymptomatic calcified lesion in the proximal femur develops sudden, severe thigh pain. Radiographs demonstrate central punctate calcifications with a new, large, adjacent aggressive radiolucent area destroying the cortex. Which of the following is the most accurate statement regarding this condition?

. The primary treatment is wide excision and the prognosis is excellent
. The new radiolucent area typically represents low-grade spindle cells
. It carries a very poor prognosis and is treated similarly to high-grade osteosarcoma
. Curettage and cementation with adjuvant radiation is the standard of care
. The histologic hallmark is the presence of physaliferous cells

Correct Answer & Explanation

. It carries a very poor prognosis and is treated similarly to high-grade osteosarcoma

Explanation

This is a classic presentation of dedifferentiated chondrosarcoma, where a low-grade cartilaginous tumor abruptly changes into a high-grade, non-cartilaginous sarcoma (such as osteosarcoma, fibrosarcoma, or undifferentiated pleomorphic sarcoma). It has a very poor prognosis. Treatment requires wide surgical resection, often combined with systemic chemotherapy tailored to the high-grade dedifferentiated component, similar to the treatment of high-grade osteosarcoma.

Question 4739

Topic: 10. Pathology and Oncology

A 48-year-old male presents with progressive proximal muscle weakness, diffuse bone pain, and multiple bilateral insufficiency fractures of the femoral necks and pubic rami. Laboratory tests show significant hypophosphatemia, elevated alkaline phosphatase, normal serum calcium, normal PTH, normal 25-OH vitamin D, and elevated FGF23 levels. Which of the following is the most likely underlying etiology?

. Multiple myeloma
. Phosphaturic mesenchymal tumor
. Metastatic prostate cancer
. Primary hyperparathyroidism
. Paget's disease of bone

Correct Answer & Explanation

. Phosphaturic mesenchymal tumor

Explanation

The patient's presentation is classic for tumor-induced osteomalacia (TIO), a paraneoplastic syndrome caused by a small, slow-growing, benign tumor (typically a phosphaturic mesenchymal tumor) that secretes Fibroblast Growth Factor 23 (FGF23). FGF23 causes renal phosphate wasting and decreases 1,25-dihydroxyvitamin D production, leading to hypophosphatemia, osteomalacia, and insufficiency fractures. Resection of the tumor is curative.

Question 4740

Topic: 10. Pathology and Oncology

A 28-year-old female presents with a slow-growing, deep, painful mass near her ankle joint. Radiographs reveal a soft tissue mass with stippled calcifications. Biopsy demonstrates a biphasic pattern of epithelial and spindle cells. Which genetic translocation is diagnostic for this tumor?

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

Correct Answer & Explanation

. t(X;18)

Explanation

Synovial sarcoma classically presents in young adults as a deep-seated mass in the extremities, often near a joint, and frequently exhibits calcifications on radiographs. The diagnostic translocation is t(X;18)(p11;q11), leading to the SYT-SSX (or SS18-SSX) fusion gene. t(11;22) is Ewing sarcoma, t(12;16) is myxoid liposarcoma, t(9;22) is extraskeletal myxoid chondrosarcoma, and t(2;13) is alveolar rhabdomyosarcoma.

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