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10. Pathology and Oncology MCQs

Practice Set 132 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 2621

Topic: 10. Pathology and Oncology

When performing an incisional biopsy for a suspected primary malignant bone tumor in the distal femur, which of the following principles must be strictly adhered to?

. Use a transverse incision to maximize cosmetic outcome
. Ensure meticulous dissection through multiple muscle compartments to access the tumor safely
. Place the longitudinal incision directly in line with the planned definitive resection
. Routinely use an exsanguinating tourniquet prior to making the incision
. Place a surgical drain exiting through a separate, laterally based stab incision

Correct Answer & Explanation

. Use a transverse incision to maximize cosmetic outcome

Explanation

A properly planned biopsy is crucial in orthopedic oncology. The biopsy incision should be longitudinal and placed perfectly in line with the definitive surgical incision, ensuring that the entire biopsy tract can be excised en bloc during the tumor resection. Transverse incisions contaminate wide tissue planes. The procedure should remain within a single compartment. While a tourniquet may be used, the limb should not be exsanguinated (e.g., with an Esmarch bandage) to avoid pushing tumor cells centrally. Drains, if used, must exit directly in line with the surgical incision so their tract can also be excised.

Question 2622

Topic: 10. Pathology and Oncology

A 12-year-old boy presents with a painful, swollen mid-shaft femur. Radiographs demonstrate a permeative, destructive lesion with an 'onion skin' periosteal reaction. Histological evaluation shows uniform small, round blue cells. The t(11;22)(q24;q12) translocation associated with this tumor results in which of the following fusion products?

. EWS-FLI1
. SYT-SSX1
. TLS-CHOP
. PAX3-FKHR
. COL1A1-PDGFB

Correct Answer & Explanation

. EWS-FLI1

Explanation

The clinical presentation and histology describe Ewing sarcoma. Over 90% of Ewing sarcomas are characterized by the t(11;22)(q24;q12) chromosomal translocation, which results in the EWS-FLI1 fusion transcript. SYT-SSX represents the t(X;18) translocation seen in synovial sarcoma. TLS-CHOP (FUS-DDIT3) is seen in myxoid liposarcoma via t(12;16). PAX3-FKHR is seen in alveolar rhabdomyosarcoma via t(2;13). COL1A1-PDGFB is characteristic of dermatofibrosarcoma protuberans.

Question 2623

Topic: 10. Pathology and Oncology

A 28-year-old man undergoes excision of a slowly growing, painful soft tissue mass in his popliteal fossa. Histology demonstrates a biphasic pattern of spindle cells and epithelial-like gland structures. Cytogenetic analysis reveals a t(X;18) translocation. Which of the following is the most appropriate next step in staging this patient?

. Bone scan
. Chest CT
. Sentinel lymph node biopsy
. Abdominal MRI
. Skeletal survey

Correct Answer & Explanation

. Bone scan

Explanation

The patient's histology and genetic profile (t(X;18)) confirm the diagnosis of synovial sarcoma. Like most high-grade soft tissue sarcomas, synovial sarcoma preferentially metastasizes hematogenously to the lungs. Therefore, a high-resolution Chest CT is the standard and most critical imaging modality for staging. Although synovial sarcoma has a slightly higher rate of regional lymph node metastasis compared to other sarcomas (along with clear cell, epithelioid, angiosarcoma, and rhabdomyosarcoma), routine sentinel lymph node biopsy is not considered the standard initial staging test over a chest CT.

Question 2624

Topic: 10. Pathology and Oncology

A 45-year-old woman presents with severe generalized bone pain and proximal muscle weakness. Laboratory studies show severe hypophosphatemia, normal serum calcium, normal parathyroid hormone, normal vitamin D, and elevated alkaline phosphatase. A skeletal survey reveals multiple pseudofractures (Looser zones). A small, benign-appearing soft tissue mass is noted on the plantar aspect of her foot. Which of the following substances is most likely being pathologically secreted by this soft tissue mass?

. Parathyroid hormone-related peptide (PTHrP)
. Fibroblast growth factor 23 (FGF-23)
. 1,25-dihydroxyvitamin D
. Insulin-like growth factor II
. Calcitonin

Correct Answer & Explanation

. Parathyroid hormone-related peptide (PTHrP)

Explanation

The patient has tumor-induced osteomalacia (oncogenic osteomalacia), a rare paraneoplastic syndrome typically caused by benign phosphaturic mesenchymal tumors. These tumors secrete Fibroblast Growth Factor 23 (FGF-23). Excess FGF-23 acts on the kidneys to severely decrease phosphate reabsorption and inhibit 1-alpha-hydroxylase, reducing the production of active 1,25-dihydroxyvitamin D. This leads to profound hypophosphatemia, causing osteomalacia. Excision of the tumor is curative.

Question 2625

Topic: 10. Pathology and Oncology

A 40-year-old man presents with chronic, dull shoulder pain. Radiographs demonstrate a radiolucent, expansile lesion strictly confined to the epiphysis of the proximal humerus with focal intralesional calcifications. Histological sections reveal lobules of cells with abundant clear cytoplasm embedded in a chondroid matrix, without significant mitotic activity. Which of the following statements regarding this condition is true?

. The tumor characteristically arises in the diaphyseal regions of long bones
. Neoadjuvant multidrug chemotherapy is the primary modality of treatment
. Wide surgical resection is the treatment of choice
. Intralesional curettage with adjuvant therapy is curative in 95% of cases
. The tumor pathogenesis is driven by a characteristic t(12;16) chromosomal translocation

Correct Answer & Explanation

. The tumor characteristically arises in the diaphyseal regions of long bones

Explanation

The clinical and microscopic findings are classic for clear cell chondrosarcoma. This rare, low-grade malignant cartilaginous tumor typically involves the epiphysis of long bones (most commonly the proximal femur and proximal humerus) in adults aged 20-50. Because it is a malignant lesion with a high rate of local recurrence and potential for metastasis if treated inadequately, intralesional curettage is contraindicated. The standard of care is wide en bloc surgical resection. Like other conventional chondrosarcomas, it is generally resistant to chemotherapy and radiotherapy.

Question 2626

Topic: 10. Pathology and Oncology

A 15-year-old boy presents with progressive knee pain. Radiographs show a 2-cm lytic lesion with a thin sclerotic margin located in the proximal tibial epiphysis. MRI confirms the purely epiphyseal location and reveals extensive surrounding bone marrow edema. Histology reveals mononuclear cells with prominent longitudinal nuclear grooves ('coffee bean' nuclei) and dispersed multinucleated giant cells within areas of 'chicken-wire' calcification. What is the most appropriate management for this lesion?

. Wide en bloc resection and endoprosthetic reconstruction
. Intralesional curettage and bone grafting
. Definitive external beam radiation therapy
. Neoadjuvant chemotherapy followed by wide resection
. Strict observation with serial radiographs every 6 months

Correct Answer & Explanation

. Wide en bloc resection and endoprosthetic reconstruction

Explanation

This patient has a chondroblastoma, a benign but locally aggressive epiphyseal tumor characteristically found in skeletally immature individuals. The classic histological features include mononuclear cells with 'coffee-bean' nuclei (longitudinal grooves) and fine, pericellular 'chicken-wire' calcification. Since it is a benign lesion, the standard treatment is thorough intralesional curettage with local adjuvant application (such as high-speed burring, phenol, or cryotherapy) followed by bone grafting or cementation. Wide resection is unnecessary and overly morbid.

Question 2627

Topic: Bone Tumors

A 9-year-old girl is evaluated for an antalgic gait and leg length discrepancy. Radiographs of her right femur reveal an expansive, 'ground-glass' intramedullary lesion with cortical thinning. On physical examination, she has large, irregularly bordered hyperpigmented macules ('coast of Maine') and signs of precocious puberty. This clinical syndrome is caused by a somatic, activating postzygotic mutation in which of the following genes?

. Fibroblast growth factor receptor 3 (FGFR3)
. Neurofibromin 1 (NF1)
. GNAS1
. PTEN
. EXT1

Correct Answer & Explanation

. Fibroblast growth factor receptor 3 (FGFR3)

Explanation

The clinical presentation describes McCune-Albright syndrome, a classic triad of polyostotic fibrous dysplasia, cafe-au-lait spots with irregular borders ('coast of Maine'), and peripheral precocious puberty (or other endocrinopathies). The syndrome is driven by a somatic, activating postzygotic missense mutation in the GNAS1 gene. This mutation causes a constituent activation of the stimulatory G-protein (Gs-alpha), leading to unregulated, sustained production of intracellular cyclic AMP (cAMP) and subsequent abnormal cell proliferation and differentiation.

Question 2628

Topic: 10. Pathology and Oncology

A 25-year-old male presents with a slow-growing, painful soft tissue mass in his foot. An MRI reveals a heterogeneous mass adjacent to the plantar fascia. Biopsy shows a biphasic histology with both spindle and epithelial cells. Molecular testing reveals a specific cytogenetic translocation. Which of the following is the most likely translocation associated with this patient's diagnosis?

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

Correct Answer & Explanation

. t(11;22)(q24;q12)

Explanation

The clinical presentation and biphasic histology (spindle and epithelial cells) strongly suggest a synovial sarcoma. Synovial sarcoma classically presents in young adults, often in the soft tissues of the extremities (especially foot and ankle). The hallmark translocation is t(X;18)(p11;q11), which results in the SYT-SSX fusion gene. Ewing sarcoma is characterized by t(11;22); myxoid liposarcoma by t(12;16); alveolar rhabdomyosarcoma by t(2;13); and extraskeletal myxoid chondrosarcoma by t(9;22).

Question 2629

Topic: 10. Pathology and Oncology

An orthopedic oncologist is planning an incisional biopsy of a suspected high-grade soft tissue sarcoma located in the anterior compartment of the thigh. Which of the following is the most critical technical principle to minimize the risk of local recurrence following definitive resection?

. The biopsy tract should be placed transverse to the muscle fibers to limit longitudinal spread.
. The biopsy incision and entire tract must be placed within the planned definitive excision block.
. A tourniquet should be inflated during the procedure and deflated only after wound closure to prevent hematoma.
. Deep fascial flaps should be widely elevated to clearly identify neurovascular structures prior to biopsy.
. The biopsy sample should primarily be taken from the central necrotic core to avoid seeding viable tumor cells.

Correct Answer & Explanation

. The biopsy tract should be placed transverse to the muscle fibers to limit longitudinal spread.

Explanation

The most critical principle of an open incisional biopsy for a suspected malignancy is that the entire biopsy tract (incision, subcutaneous tissue, and deeper tissues) must be cleanly excisable en bloc with the tumor during definitive surgery. Transverse incisions in the extremity must be avoided as they contaminate multiple compartments and require a much larger resection block. If a tourniquet is used, it should be deflated before closure to ensure meticulous hemostasis; post-operative hematoma can spread tumor cells extensively. Elevating large flaps contaminates normal tissue planes. Biopsying the necrotic core yields non-diagnostic, dead tissue.

Question 2630

Topic: 10. Pathology and Oncology

A 15-year-old boy presents with severe night pain in his right mid-thigh that is dramatically relieved within 30 minutes of taking ibuprofen. Radiographs demonstrate a 10 mm radiolucent nidus surrounded by dense, sclerotic reactive bone in the femoral diaphysis. What biochemical mediator is produced in high amounts by this tumor, directly responsible for the intense localized pain?

. Tumor necrosis factor-alpha (TNF-alpha)
. Prostaglandin E2 (PGE2)
. Interleukin-1 (IL-1)
. Transforming growth factor-beta (TGF-beta)
. Bone morphogenetic protein (BMP)

Correct Answer & Explanation

. Tumor necrosis factor-alpha (TNF-alpha)

Explanation

The patient's clinical presentation (severe night pain dramatically relieved by NSAIDs) and radiographic findings are pathognomonic for an osteoid osteoma. The tumor cells within the nidus produce extremely high levels of cyclooxygenase-2 (COX-2), leading to the robust local production of Prostaglandin E2 (PGE2). PGE2 causes local vasodilation and intense, characteristic pain. The rapid and dramatic relief of symptoms following NSAID administration is directly due to the pharmacological inhibition of COX enzymes and subsequent suppression of PGE2 synthesis.

Question 2631

Topic: 10. Pathology and Oncology

A 45-year-old man presents with a 6-cm painless, deep-seated soft tissue mass in the anterior thigh. An MRI confirms a heterogeneous, enhancing lesion within the quadriceps muscle. Which of the following is the most appropriate principle when performing a core needle or incisional biopsy of this mass?

. The biopsy tract should be placed transverse to the long axis of the extremity.
. Meticulous hemostasis is not required if a drain is placed.
. The biopsy tract must be excised en bloc with the tumor during definitive resection.
. Core needle biopsy should be avoided due to the high risk of tumor seeding.
. The biopsy should traverse uninvolved compartments to avoid local contamination.

Correct Answer & Explanation

. The biopsy tract should be placed transverse to the long axis of the extremity.

Explanation

A core or incisional biopsy of a suspected sarcoma must be carefully planned. The most critical principle is that the biopsy tract must be considered contaminated with tumor cells and should be excised en bloc with the definitive specimen. Incisions should be longitudinal (in line with the extremity), strict hemostasis must be achieved to prevent a contaminated hematoma, and uninvolved compartments must be strictly avoided.

Question 2632

Topic: 10. Pathology and Oncology

A 28-year-old woman presents with a slowly enlarging, painful mass around her knee, which she first noticed 6 months ago. MRI shows a well-circumscribed soft tissue mass near the joint line. Core needle biopsy reveals a biphasic tumor with both epithelial and spindle cell components. Which of the following cytogenetic translocations is diagnostic of this tumor?

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

Correct Answer & Explanation

. t(11;22)

Explanation

The patient has a synovial sarcoma, which classically presents near a joint in young adults and often demonstrates biphasic histology (epithelial and spindle cells). It is genetically characterized by the t(X;18)(p11;q11) translocation, which results in the SYT-SSX fusion gene. Translocation t(11;22) is seen in Ewing sarcoma, t(12;16) in myxoid liposarcoma, and t(2;13) in alveolar rhabdomyosarcoma.

Question 2633

Topic: Bone Tumors

A 14-year-old boy presents with pain and swelling in his left shoulder. Radiographs show an expansile, lytic lesion in the proximal humerus. Magnetic resonance imaging demonstrates multiple 'fluid-fluid levels'. A core needle biopsy confirms an aneurysmal bone cyst. Which of the following genetic abnormalities is considered the primary driver of this neoplastic lesion?

. GNAS mutation
. EXT1 mutation
. TP53 mutation
. USP6 gene rearrangement
. RUNX2 deletion

Correct Answer & Explanation

. GNAS mutation

Explanation

Primary aneurysmal bone cysts (ABCs) were historically considered reactive lesions but are now recognized as true neoplasms driven by specific genetic alterations. Up to 70% of primary ABCs harbor rearrangements of the USP6 gene, most commonly t(16;17). GNAS mutations are associated with fibrous dysplasia, and EXT1 mutations are seen in multiple hereditary exostoses.

Question 2634

Topic: 10. Pathology and Oncology

A 40-year-old man presents with a lytic lesion in the proximal femoral epiphysis. Radiographs show a well-defined lucency with central calcifications. Histology reveals sheets of cells with abundant clear cytoplasm, distinct cell membranes, and interspersed areas of chondroid matrix. What is the most appropriate management for this condition?

. Intralesional curettage and bone grafting
. Wide en bloc resection
. Preoperative radiation therapy followed by curettage
. Systemic chemotherapy and limb salvage
. Radiofrequency ablation

Correct Answer & Explanation

. Intralesional curettage and bone grafting

Explanation

The clinical and histological presentation is highly characteristic of clear cell chondrosarcoma. Unlike chondroblastoma (which is typically seen in younger patients and treated with curettage), clear cell chondrosarcoma is a low-grade malignant bone tumor. It generally does not respond to radiation or chemotherapy, and intralesional curettage carries a high risk of recurrence. Wide en bloc resection is the standard of care.

Question 2635

Topic: 10. Pathology and Oncology

A 45-year-old man presents with a painless, deep mass in his posterior thigh. MRI reveals a large, multilobulated mass that is hyperintense on T2-weighted images with nodular enhancement. A core biopsy shows a prominent myxoid stroma with a 'plexiform' capillary network and lipoblasts. Molecular testing confirms a t(12;16) translocation. What is the most common site of metastasis for this specific tumor type, dictating specialized staging imaging?

. Lungs
. Liver
. Brain
. Extrapulmonary bone and spine
. Inguinal lymph nodes

Correct Answer & Explanation

. Lungs

Explanation

Myxoid liposarcoma is characterized by the t(12;16) translocation resulting in the FUS-DDIT3 fusion gene. Unlike most high-grade soft tissue sarcomas which primarily metastasize to the lungs, myxoid liposarcoma has a strong predilection for extrapulmonary metastasis, particularly to the bone and spine. A whole-spine MRI is typically recommended for staging.

Question 2636

Topic: 10. Pathology and Oncology

A 14-year-old girl recently underwent wide resection of a conventional high-grade osteosarcoma of the distal femur following a standard 10-week course of neoadjuvant chemotherapy. Which of the following factors is the most significant prognostic indicator for her overall survival?

. Size of the primary tumor at initial presentation
. Histologic subtype of the osteosarcoma
. Degree of tumor necrosis in the resected specimen
. Type of definitive surgical reconstruction performed
. Distance of the tumor margin from the joint capsule

Correct Answer & Explanation

. Size of the primary tumor at initial presentation

Explanation

In patients with conventional high-grade osteosarcoma, the degree of tumor necrosis in the resected surgical specimen following neoadjuvant chemotherapy is the single most important prognostic factor for overall survival. A good response is typically defined as 90% or greater tumor necrosis.

Question 2637

Topic: 10. Pathology and Oncology

A 29-year-old woman presents with a slowly growing, firm mass in her right shoulder girdle. Core biopsy reveals a proliferation of uniform spindle cells in a collagenous stroma with a lack of significant atypia or mitoses. Immunohistochemistry is strongly positive for nuclear beta-catenin. According to current evidence-based guidelines, what is the most appropriate initial management for this patient?

. Wide surgical excision with negative margins
. Marginal excision followed by adjuvant radiation
. Active surveillance (Wait-and-see approach)
. Neoadjuvant doxorubicin-based chemotherapy
. Forequarter amputation

Correct Answer & Explanation

. Wide surgical excision with negative margins

Explanation

The diagnosis is a desmoid tumor (aggressive fibromatosis), characterized by uniform spindle cells and nuclear beta-catenin positivity. Because desmoid tumors do not metastasize, can regress spontaneously, and have high recurrence rates even with negative surgical margins, current guidelines recommend 'active surveillance' or a 'wait-and-see' approach as the first line of management for asymptomatic or mildly symptomatic lesions.

Question 2638

Topic: 10. Pathology and Oncology

A 35-year-old woman with recurrent, diffuse tenosynovial giant cell tumor (pigmented villonodular synovitis) of the knee has failed multiple extensive open synovectomies. Her disease is driven by a specific genetic translocation [t(1;2)] causing overexpression of a particular cytokine. Which of the following targeted systemic therapies is most appropriate to manage her severe, symptomatic disease?

. Denosumab
. Imatinib
. Sorafenib
. Pexidartinib
. Rituximab

Correct Answer & Explanation

. Denosumab

Explanation

Diffuse tenosynovial giant cell tumor (TGCT / PVNS) is driven by a chromosomal translocation involving the CSF1 gene, leading to excessive production of Colony-Stimulating Factor 1 (CSF-1). Pexidartinib is a CSF-1 receptor (CSF1R) inhibitor that specifically targets this pathway and is approved for adults with symptomatic TGCT not amenable to improvement with surgery.

Question 2639

Topic: 10. Pathology and Oncology

A 30-year-old man with a known history of neurofibromatosis type 1 (NF1) presents with rapid enlargement and new onset of severe pain in a pre-existing mass in his sciatic nerve. MRI demonstrates a large, heterogeneous mass with perilesional edema. A core needle biopsy is consistent with a high-grade malignant peripheral nerve sheath tumor (MPNST). The underlying syndrome is caused by a mutation in a gene that encodes a protein responsible for negatively regulating which of the following signaling pathways?

. Wnt/beta-catenin pathway
. RAS/MAPK pathway
. PI3K/AKT pathway
. Hedgehog pathway
. Notch signaling pathway

Correct Answer & Explanation

. Wnt/beta-catenin pathway

Explanation

Neurofibromatosis type 1 (NF1) is caused by mutations in the NF1 gene, which encodes neurofibromin. Neurofibromin functions as a GTPase-activating protein (GAP) that negatively regulates the RAS signaling pathway. Loss of neurofibromin leads to hyperactive RAS/MAPK signaling, predisposing patients to neurofibromas and MPNSTs.

Question 2640

Topic: 10. Pathology and Oncology

A 25-year-old male presents with a slowly enlarging, painless mass around his left knee. MRI shows a well-defined, multilobulated soft-tissue mass adjacent to the joint. Biopsy reveals a biphasic pattern of spindle cells and epithelial cells. What is the most common cytogenetic abnormality associated with this condition?

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

Correct Answer & Explanation

. t(11;22)

Explanation

The clinical and histologic findings are characteristic of synovial sarcoma, which frequently features a biphasic pattern of spindle and epithelial cells. The characteristic cytogenetic abnormality is t(X;18)(p11;q11), resulting in the SYT-SSX fusion gene. t(11;22) is associated with Ewing sarcoma. t(9;22) is seen in extraskeletal myxoid chondrosarcoma. t(12;16) is seen in myxoid liposarcoma. t(2;13) is seen in alveolar rhabdomyosarcoma.

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