Menu

10. Pathology and Oncology MCQs

Practice Set 145 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 2881

Topic: 10. Pathology and Oncology

A 32-year-old woman presents with a slowly enlarging, painless mass around her right knee that has been present for 2 years. MRI reveals a well-circumscribed, heterogeneous soft-tissue mass adjacent to, but not within, the joint space. A biopsy is performed, revealing a biphasic pattern of spindle cells and epithelial cells. What chromosomal abnormality is most characteristic of this tumor?

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

Correct Answer & Explanation

. t(X;18)

Explanation

The clinical and histologic description represents a synovial sarcoma. Synovial sarcomas often present as slow-growing masses in young adults, typically near large joints (especially the knee) but rarely intra-articular. Histologically, they can be biphasic (containing both spindle and epithelial cells) or monophasic. The pathognomonic chromosomal translocation is t(X;18)(p11;q11), which fuses the SYT gene on chromosome 18 with SSX1, SSX2, or SSX4 on the X chromosome.

Question 2882

Topic: 10. Pathology and Oncology

A 55-year-old man presents with dull aching pain in his right shoulder. Radiographs demonstrate a lytic lesion in the proximal humerus with intralesional 'popcorn' calcifications and focal endosteal scalloping greater than two-thirds of the cortical thickness. Which of the following features most strongly suggests a diagnosis of secondary chondrosarcoma rather than a benign enchondroma?

. Presence of calcified matrix
. Location in the proximal humerus
. Pain and deep endosteal scalloping
. Patient age
. Sclerotic margin

Correct Answer & Explanation

. Pain and deep endosteal scalloping

Explanation

Differentiating between an enchondroma and a low-grade chondrosarcoma can be challenging. Clinical symptoms (pain at rest or night pain that is not activity-related) and radiographic features such as endosteal scalloping of more than two-thirds of the cortical thickness, cortical breakthrough, or an associated soft tissue mass are concerning for malignancy. Intralesional calcification and location in the proximal humerus can be seen in both, but deep endosteal scalloping and pain in the absence of fracture strongly suggest chondrosarcoma.

Question 2883

Topic: 10. Pathology and Oncology

A 65-year-old man complains of lower back pain and generalized fatigue. Radiographs show multiple 'punched-out' lytic lesions in his skull and vertebral bodies. Laboratory evaluation reveals hypercalcemia, anemia, and an M-spike on serum protein electrophoresis. Which of the following is the most likely finding on bone marrow biopsy?

. Atypical chondrocytes with binucleation
. Small blue cells with scant cytoplasm
. Monoclonal proliferation of plasma cells
. Multinucleated giant cells in a background of mononuclear stromal cells
. Spindle cells producing osteoid matrix

Correct Answer & Explanation

. Monoclonal proliferation of plasma cells

Explanation

The presentation is classic for multiple myeloma, which is characterized by the CRAB criteria (HyperCalcemia, Renal involvement, Anemia, Bone lytic lesions). It is a hematologic malignancy characterized by the monoclonal proliferation of plasma cells in the bone marrow. Bone marrow biopsy typically shows >10% clonal plasma cells.

Question 2884

Topic: Bone Tumors

A 12-year-old girl is evaluated for a noticeable leg length discrepancy and a limp. Radiographs of her left femur show an expansive, purely lytic lesion with a 'ground-glass' appearance and a characteristic 'shepherd's crook' deformity of the proximal femur. This condition is caused by a somatic activating mutation in which of the following?

. GNAS1 gene
. EXT1 gene
. FGFR3 gene
. RB1 gene
. p53 gene

Correct Answer & Explanation

. GNAS1 gene

Explanation

The clinical and radiographic findings describe fibrous dysplasia, specifically involving the proximal femur leading to a 'shepherd's crook' deformity. Fibrous dysplasia is caused by a somatic, activating missense mutation in the GNAS1 gene, which encodes the alpha subunit of the stimulatory G protein (Gs-alpha). This mutation leads to an overproduction of cAMP, affecting the differentiation of bone marrow stromal cells.

Question 2885

Topic: 10. Pathology and Oncology

A 15-year-old boy presents with knee pain and a destructive lesion in the distal femur. Core needle biopsy confirms high-grade intramedullary osteosarcoma. He undergoes neoadjuvant chemotherapy followed by limb-salvage surgery. Which of the following is the most important prognostic factor for long-term survival in this patient?

. Age of the patient at presentation
. Tumor volume prior to chemotherapy
. Percentage of tumor necrosis on histologic mapping
. Specific histologic subtype (e.g., osteoblastic vs. chondroblastic)
. Distal versus proximal extremity location

Correct Answer & Explanation

. Percentage of tumor necrosis on histologic mapping

Explanation

The percentage of tumor necrosis on histologic mapping following neoadjuvant chemotherapy (Huvos grading system) is the most important prognostic factor for long-term survival in patients with non-metastatic high-grade intramedullary osteosarcoma. A good response is typically defined as 90% or greater tumor necrosis.

Question 2886

Topic: Bone Tumors

A 9-year-old boy presents with a 3-month history of deep, aching pain in his proximal femur that worsens at night. He reports dramatic relief of his symptoms 30 minutes after taking ibuprofen. Radiographs and a CT scan reveal a 7-mm radiolucent nidus surrounded by dense, reactive cortical sclerosis. The intense pain experienced by this patient is most directly mediated by elevated levels of which of the following substances produced by the nidus?

. Interleukin-1
. Tumor necrosis factor-alpha
. Prostaglandin E2
. Substance P
. Bradykinin

Correct Answer & Explanation

. Prostaglandin E2

Explanation

The patient has a classic presentation of an osteoid osteoma. Osteoid osteomas secrete high levels of prostaglandins, particularly Prostaglandin E2 (PGE2), which mediates the severe pain and the characteristic vasodilation around the lesion. This is the physiological basis for the dramatic pain relief provided by nonsteroidal anti-inflammatory drugs (NSAIDs).

Question 2887

Topic: 10. Pathology and Oncology

A 45-year-old man presents with chronic lower back and perineal pain associated with a palpable presacral mass. A biopsy of the lesion reveals cells with copious, vacuolated (bubbly) cytoplasm arranged in cords within a myxoid stroma. Immunohistochemistry is strongly positive for cytokeratin, epithelial membrane antigen (EMA), and brachyury. What is the most likely diagnosis?

. Chondrosarcoma
. Chordoma
. Myxopapillary ependymoma
. Giant cell tumor of the sacrum
. Metastatic clear cell renal cell carcinoma

Correct Answer & Explanation

. Chordoma

Explanation

Chordoma is a rare, locally aggressive malignant tumor arising from embryonic remnants of the notochord, most commonly located in the sacrum or clivus. Histologically, it is characterized by physaliferous cells (large cells with bubbly, vacuolated cytoplasm). Chordomas consistently express brachyury, a transcription factor essential for notochord development, which distinguishes them from chondrosarcoma and other sacral tumors.

Question 2888

Topic: 10. Pathology and Oncology

A 22-year-old man presents with a slow-growing, painless soft-tissue mass in the popliteal fossa. MRI demonstrates a deeply seated mass that is intimately associated with the joint capsule but does not involve the intra-articular space. Biopsy reveals a biphasic spindle cell neoplasm. Which of the following chromosomal translocations is most characteristic of 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)(q22;q12)

Correct Answer & Explanation

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

Explanation

Synovial sarcoma typically occurs in young adults as a slow-growing mass near a large joint (most commonly the knee), though it rarely involves the synovial tissue directly. It is cytogenetically characterized by the t(X;18)(p11;q11) translocation, which fuses the SS18 gene with an SSX gene (SSX1, SSX2, or SSX4). Ewing sarcoma has t(11;22), myxoid liposarcoma has t(12;16), and alveolar rhabdomyosarcoma has t(2;13).

Question 2889

Topic: 10. Pathology and Oncology

A 65-year-old woman with a history of breast cancer presents with a new metastatic lesion in her femur. You are evaluating her risk for an impending pathologic fracture using the Mirels' criteria. According to this scoring system, which combination of lesion characteristics yields the highest score, indicating the strongest recommendation for prophylactic internal fixation?

. Upper extremity location, blastic nature, size less than 1/3 of the cortex, mild pain
. Lower extremity location, lytic nature, size greater than 2/3 of the cortex, severe pain
. Spine location, mixed blastic/lytic nature, size 1/3 to 2/3 of the cortex, moderate pain
. Upper extremity location, lytic nature, size 1/3 to 2/3 of the cortex, moderate pain
. Lower extremity location, blastic nature, size less than 1/3 of the cortex, severe pain

Correct Answer & Explanation

. Lower extremity location, lytic nature, size greater than 2/3 of the cortex, severe pain

Explanation

The Mirels' criteria assess fracture risk in metastatic bone disease based on four parameters (1 to 3 points each): Site (Upper limb=1, Lower limb=2, Peritrochanteric=3), Pain (Mild=1, Moderate=2, Severe=3), Lesion type (Blastic=1, Mixed=2, Lytic=3), and Size (<1/3 cortex=1, 1/3-2/3 cortex=2, >2/3 cortex=3). A lower extremity lesion (2 or 3), lytic nature (3), size > 2/3 cortex (3), and severe pain (3) result in the highest possible combination of points among the choices, easily exceeding the threshold score of 9, which indicates a high risk of fracture and a strong indication for prophylactic fixation.

Question 2890

Topic: 10. Pathology and Oncology

A 14-year-old girl is diagnosed with Ewing sarcoma of the diaphyseal fibula following a biopsy. As part of her initial staging workup, a chest CT, whole-body MRI, and bone marrow aspirate are ordered. What is the most common site of distant metastasis for Ewing sarcoma at the time of initial presentation?

. Brain
. Liver
. Lungs
. Regional lymph nodes
. Contralateral extremity

Correct Answer & Explanation

. Lungs

Explanation

In patients with Ewing sarcoma, up to 25% have detectable metastases at presentation. The most common site of metastasis is the lungs, followed by bone and bone marrow. Therefore, a high-resolution CT scan of the chest is a critical component of the initial staging process.

Question 2891

Topic: Bone Tumors

A 35-year-old man presents with a locally aggressive, osteolytic lesion in the epiphysis of his distal radius. Histopathologic examination reveals abundant, evenly distributed multinucleated osteoclast-like giant cells in a background of round to oval mononuclear cells. Which of the following genetic alterations is highly specific for the neoplastic cells in this tumor?

. GNAS mutation
. H3F3A mutation
. EXT1 mutation
. IDH1 mutation
. PTEN mutation

Correct Answer & Explanation

. H3F3A mutation

Explanation

Giant cell tumor of bone (GCTB) is characterized by a high frequency of somatic mutations in the H3F3A gene, which encodes the histone H3.3 variant. This mutation (most commonly G34W) is found in the mononuclear neoplastic stromal cells, not the reactive giant cells, and is a highly specific diagnostic marker for GCTB. GNAS mutations are seen in fibrous dysplasia, EXT1/2 in osteochondromas, and IDH1/2 in enchondromas and chondrosarcomas.

Question 2892

Topic: 10. Pathology and Oncology

A 10-year-old boy presents with swelling and pain in his left thigh. Radiographs reveal a destructive permeative lesion in the femoral diaphysis with an "onion-skin" periosteal reaction. Biopsy demonstrates sheets of uniform, small round blue cells with scant cytoplasm. Immunohistochemical analysis is requested. Staining for which of the following cell surface markers is most characteristically positive in this tumor?

. CD99
. CD45
. CD20
. MyoD1
. S-100

Correct Answer & Explanation

. CD99

Explanation

The clinical, radiographic, and histologic presentation is classic for Ewing sarcoma. The cells of Ewing sarcoma strongly express the MIC2 gene product, identified by the CD99 immunohistochemical stain. While CD99 can also be expressed in some other small round blue cell tumors, strong, diffuse membranous staining is a hallmark of Ewing sarcoma. CD45 and CD20 are lymphoid markers, MyoD1 is for rhabdomyosarcoma, and S-100 highlights neural, melanocytic, or cartilaginous tumors.

Question 2893

Topic: 10. Pathology and Oncology

A 55-year-old man undergoes wide surgical resection of a painless, 8-cm mass located deep within the vastus lateralis of his anterior thigh. Histopathology reveals an undifferentiated pleomorphic sarcoma with high-grade features. The surgical margins are reported as negative (R0). To minimize the risk of local recurrence, what is the most appropriate adjuvant therapy for this patient?

. Adjuvant denosumab
. Postoperative radiation therapy
. Systemic immunotherapy with pembrolizumab
. Radiofrequency ablation
. Imatinib mesylate therapy

Correct Answer & Explanation

. Postoperative radiation therapy

Explanation

For deep, large (> 5 cm), and high-grade soft tissue sarcomas of the extremity, wide surgical excision combined with radiation therapy (either neoadjuvant or adjuvant) is the standard of care to maximize local control. Radiation therapy significantly reduces the rate of local recurrence compared to surgery alone. Imatinib is targeted therapy for dermatofibrosarcoma protuberans or GIST, and denosumab is for giant cell tumors.

Question 2894

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with an aggressive diaphyseal lesion in his femur with a large soft tissue mass. Biopsy reveals small round blue cells. Cytogenetics confirm a t(11;22) translocation. Which of the following is the resulting fusion protein responsible for driving the pathogenesis?

. SYT-SSX
. EWS-FLI1
. EWS-ATF1
. FUS-CHOP
. PAX3-FKHR

Correct Answer & Explanation

. EWS-FLI1

Explanation

Ewing sarcoma is classically associated with the t(11;22)(q24;q12) translocation, which occurs in about 85% of cases and results in the EWS-FLI1 fusion protein. This acts as an aberrant transcription factor. SYT-SSX is seen in synovial sarcoma t(X;18). EWS-ATF1 is associated with clear cell sarcoma t(12;22). FUS-CHOP is seen in myxoid liposarcoma t(12;16). PAX3-FKHR is seen in alveolar rhabdomyosarcoma t(2;13).

Question 2895

Topic: 10. Pathology and Oncology

A 40-year-old man presents with chronic, recurrent hemarthrosis of the knee without a history of trauma or coagulopathy. MRI demonstrates a large, nodular synovial mass with blooming artifact on gradient-echo sequences. Which genetic alteration is most characteristic of this condition?

. Overexpression of Colony Stimulating Factor 1 (CSF1) due to t(1;2) translocation
. Amplification of MDM2 and CDK4
. Point mutation in the GNAS1 gene
. Inactivation of the EXT1 tumor suppressor gene
. Translocation t(11;22) involving the EWSR1 gene

Correct Answer & Explanation

. Overexpression of Colony Stimulating Factor 1 (CSF1) due to t(1;2) translocation

Explanation

Pigmented villonodular synovitis (PVNS), also known as tenosynovial giant cell tumor (TGCT), is driven by a neoplastic clone of cells that overexpress CSF1, typically due to a t(1;2) translocation. The excess CSF1 acts as a chemoattractant, recruiting a large number of non-neoplastic macrophages (which form the bulk of the tumor mass) via the CSF1 receptor. MDM2/CDK4 amplification is characteristic of atypical lipomatous tumor/well-differentiated liposarcoma and parosteal osteosarcoma. GNAS1 mutation is found in fibrous dysplasia.

Question 2896

Topic: 10. Pathology and Oncology
A 55-year-old man presents with increasing thigh pain. Radiographs reveal a large calcified lesion in the medullary canal of the proximal femur with endosteal scalloping greater than two-thirds of the cortical thickness and a focal area of cortical breakthrough. Biopsy demonstrates a Grade II (intermediate grade) conventional chondrosarcoma. What is the most appropriate management?
. Neoadjuvant chemotherapy followed by wide surgical resection
. Intralesional curettage, high-speed burring, and cementation
. Wide surgical resection alone
. Radiation therapy followed by intralesional curettage
. Neoadjuvant radiation therapy followed by wide surgical resection

Correct Answer & Explanation

. Wide surgical resection alone

Explanation

Conventional chondrosarcomas (Grades II and III) are notably resistant to both chemotherapy and radiation therapy due to their poor vascularity, slow growth, and high extracellular matrix content. The standard of care for a Grade II or III conventional chondrosarcoma is wide surgical resection. Intralesional curettage is reserved for benign cartilaginous lesions (enchondroma) or carefully selected low-grade (Atypical Cartilaginous Tumors) lesions.

Question 2897

Topic: 10. Pathology and Oncology

A 28-year-old woman presents with a slow-growing, painless mass at the posterior aspect of her distal femur. Radiographs show a dense, heavily ossified mass attached to the posterior cortex by a broad base, with a 'string sign' radiolucent cleft separating the tumor from the underlying cortex. A biopsy confirms a low-grade malignant bone-forming tumor. What is the classic genetic amplification associated with this specific tumor?

. EWS-FLI1
. MDM2 and CDK4
. c-MYC
. SS18-SSX1
. GNAS

Correct Answer & Explanation

. MDM2 and CDK4

Explanation

The clinical and radiographic presentation (posterior distal femur location, dense mass, 'string sign') is classic for parosteal osteosarcoma, a low-grade surface osteosarcoma. Molecularly, parosteal osteosarcoma is characterized by supernumerary ring chromosomes containing amplified segments of chromosome 12q13-15, which leads to the amplification of the MDM2 and CDK4 genes. Identifying this amplification is vital to differentiate it from reactive lesions like heterotopic ossification.

Question 2898

Topic: 10. Pathology and Oncology

A 15-year-old boy presents with a painful mass in his diaphyseal femur. Radiographs show a permeative lesion with a "moth-eaten" appearance and a "periosteal onion-skin" reaction. Biopsy reveals small round blue cells. Immunohistochemistry is strongly positive for CD99. Which of the following genetic translocations is most characteristic of 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) (q22;q12)

Correct Answer & Explanation

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

Explanation

The clinical scenario describes Ewing sarcoma, which is classically associated with the t(11;22)(q24;q12) translocation, resulting in the EWS-FLI1 fusion protein. Synovial sarcoma is associated with t(X;18)(p11;q11). Myxoid liposarcoma has t(12;16)(q13;p11). Alveolar rhabdomyosarcoma has t(2;13)(q35;q14). Extraskeletal myxoid chondrosarcoma has t(9;22).

Question 2899

Topic: 10. Pathology and Oncology

A 14-year-old boy is diagnosed with high-grade conventional osteosarcoma of the proximal tibia. He undergoes neoadjuvant chemotherapy followed by wide surgical resection. Which of the following factors obtained from the surgical specimen is the most important prognostic indicator for his long-term survival?

. Surgical margin of exactly 1 cm
. Tumor necrosis rate greater than 90%
. Presence of distinct cartilaginous differentiation in the tumor
. High expression of p53 in the resected tissue
. Presence of Codman triangle on postoperative imaging

Correct Answer & Explanation

. Tumor necrosis rate greater than 90%

Explanation

The most important prognostic factor for long-term survival in patients with localized high-grade osteosarcoma is the histologic response to neoadjuvant chemotherapy. A tumor necrosis rate of >90% (indicative of a good responder) is associated with significantly better overall survival compared to a poor response (<90% necrosis).

Question 2900

Topic: 10. Pathology and Oncology

A 45-year-old man presents with a deep, painless, slowly growing mass in his thigh. MRI reveals a large intramuscular lesion with high signal intensity on T2-weighted images and a lipomatous component. Biopsy confirms myxoid liposarcoma. Due to the specific biology of this tumor, which of the following imaging modalities should be included in the staging workup that is not typically routine for other high-grade soft tissue sarcomas of the extremity?

. Radiograph of the contralateral extremity
. PET-CT of the brain
. Non-contrast CT of the abdomen
. MRI of the entire spine
. Ultrasound of the regional lymph nodes

Correct Answer & Explanation

. MRI of the entire spine

Explanation

Myxoid liposarcoma has a unique propensity to metastasize to extrapulmonary sites, particularly other soft tissues, the retroperitoneum, and bone (frequently the spine). Therefore, staging should include an MRI of the entire spine to detect osseous metastases, in addition to standard chest imaging.

Test Yourself

Switch to an interactive, timed exam simulation to truly master this topic.

On this Page