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10. Pathology and Oncology MCQs

Practice Set 146 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 2901

Topic: 10. Pathology and Oncology
A 55-year-old man presents with deep pelvic pain. Radiographs show a large destructive lytic lesion in the right ilium with 'popcorn' intralesional calcifications. Biopsy demonstrates atypical chondrocytes with binucleated cells and myxoid stroma, consistent with grade II chondrosarcoma. What is the standard of care for this localized tumor?
. Neoadjuvant chemotherapy followed by wide surgical resection
. Preoperative radiation therapy followed by intralesional curettage
. Wide surgical resection alone
. Intralesional curettage, adjuvant phenol, and cementation
. Primary external beam radiation therapy

Correct Answer & Explanation

. Wide surgical resection alone

Explanation

Chondrosarcomas (particularly intermediate to high grade, like grade II or III) are notoriously resistant to both conventional chemotherapy and radiation therapy. The standard of care for localized intermediate or high-grade chondrosarcoma is wide surgical resection alone.

Question 2902

Topic: Bone Tumors

A 14-year-old girl presents with a rapidly enlarging mass in her proximal fibula. Radiographs reveal an eccentric, expansile, purely lytic metaphyseal lesion with a thin 'eggshell' cortical rim. MRI demonstrates multiple fluid-fluid levels. Genetic analysis of the primary lesion would most likely reveal a translocation involving which of the following genes?

. USP6
. EXT1
. GNAS
. RUNX2
. COL1A1

Correct Answer & Explanation

. USP6

Explanation

Primary Aneurysmal Bone Cysts (ABCs) are neoplastic processes characterized by translocations involving the USP6 gene on chromosome 17p13. EXT1 is associated with multiple hereditary exostoses. GNAS mutations are seen in fibrous dysplasia. RUNX2 mutations cause cleidocranial dysplasia. COL1A1 mutations are seen in osteogenesis imperfecta.

Question 2903

Topic: 10. Pathology and Oncology

A 15-year-old boy presents with an osteosarcoma of the proximal tibia. His family history is notable for a mother who developed early-onset breast cancer at age 32 and an uncle diagnosed with a soft-tissue sarcoma at age 25. A germline mutation in which of the following genes is the most likely underlying cause of this patient's familial cancer syndrome?

. RB1
. TP53
. EXT1
. GNAS
. NF1

Correct Answer & Explanation

. TP53

Explanation

This patient's presentation and strong family history of early-onset malignancies (breast cancer, sarcomas) are highly indicative of Li-Fraumeni syndrome. Li-Fraumeni syndrome is a rare autosomal dominant disorder caused by a germline mutation in the TP53 tumor suppressor gene, which regulates the cell cycle and apoptosis. Patients with this syndrome are at a significantly increased risk of developing osteosarcoma, soft-tissue sarcomas, early-onset breast cancer, brain tumors, leukemia, and adrenocortical carcinoma. Although mutations in RB1 (associated with hereditary retinoblastoma) also increase the risk for osteosarcoma, the specific constellation of tumors in this patient's family points directly to TP53. EXT1 is associated with multiple hereditary exostoses, GNAS with fibrous dysplasia (McCune-Albright syndrome), and NF1 with neurofibromatosis type 1.

Question 2904

Topic: 10. Pathology and Oncology

A 10-year-old boy is evaluated for worsening pain and swelling in his left thigh. Plain radiographs show a permeative diaphyseal lesion in the femur with an associated 'onion-skin' periosteal reaction. A biopsy is performed, revealing uniform sheets of small, round, blue cells with scant cytoplasm. Immunohistochemistry is positive for CD99. Which of the following chromosomal translocations is most strongly associated with this neoplasm?

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

Correct Answer & Explanation

. t(11;22)

Explanation

The patient's clinical and histological findings (diaphyseal permeative lesion, 'onion-skin' periosteal reaction, small round blue cells, CD99 positivity) are classic for Ewing sarcoma. Ewing sarcoma is driven by specific chromosomal translocations that fuse the EWS gene on chromosome 22 with an ETS-family transcription factor gene. The most common translocation, found in approximately 85% of cases, is t(11;22)(q24;q12), which results in the EWS-FLI1 fusion protein. Other translocations: t(X;18) is pathognomonic for synovial sarcoma; t(12;16) is associated with myxoid liposarcoma; t(2;13) is characteristic of alveolar rhabdomyosarcoma; and t(9;22) is seen in chronic myelogenous leukemia (Philadelphia chromosome) as well as extraskeletal myxoid chondrosarcoma.

Question 2905

Topic: Bone Tumors

A 22-year-old man has a 6-month history of a dull, aching pain in his posterior neck. He notes that the pain is constant and is not consistently relieved by over-the-counter NSAIDs. A CT scan of the cervical spine reveals a 2.5-cm radiolucent nidus surrounded by a thin rim of reactive sclerosis located in the posterior elements of C5. Histological examination of a biopsy specimen reveals interconnected, disorganized trabeculae of woven bone lined by prominent osteoblasts within a highly vascularized connective tissue stroma. What is the most likely diagnosis?

. Osteoid osteoma
. Osteoblastoma
. Aneurysmal bone cyst
. Chondroblastoma
. Giant cell tumor of bone

Correct Answer & Explanation

. Osteoblastoma

Explanation

The clinical, radiographic, and histological findings are indicative of an osteoblastoma. Histologically, osteoblastoma and osteoid osteoma appear virtually identical, characterized by a highly vascularized stroma and interlacing trabeculae of woven bone lined by numerous plump osteoblasts. They are primarily differentiated based on their clinical behavior and size. Osteoblastomas are classically larger than 2 cm in diameter and have a predilection for the posterior elements of the spine (similar to osteoid osteoma, but generally larger). Clinically, the pain associated with osteoblastoma is usually a dull ache that is less predictably nocturnal and is not as dramatically relieved by NSAIDs or salicylates compared to the classic presentation of osteoid osteoma. Aneurysmal bone cysts often have blood-filled cavernous spaces, while chondroblastoma typically occurs in the epiphysis and features chondroblasts with 'chicken-wire' calcifications.

Question 2906

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with an 8-week history of thigh pain and swelling. Radiographs reveal a permeative, diaphyseal lesion with a periosteal 'onion-skin' reaction in the femur. A core needle biopsy demonstrates sheets of small round blue cells. Which of the following genetic translocations is most commonly associated with this patient's diagnosis?

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

Correct Answer & Explanation

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

Explanation

The clinical and radiographic presentation is classic for Ewing sarcoma. The most common genetic translocation in Ewing sarcoma is t(11;22)(q24;q12), which results in the EWS-FLI1 fusion protein and is found in approximately 85-90% of cases. t(X;18) is associated with synovial sarcoma; t(2;13) is associated with alveolar rhabdomyosarcoma; t(12;16) is associated with myxoid liposarcoma; and t(9;22) is seen in chronic myelogenous leukemia (Philadelphia chromosome) as well as extraskeletal myxoid chondrosarcoma.

Question 2907

Topic: 10. Pathology and Oncology

A 55-year-old man undergoes wide excision of a deep soft-tissue mass in his anterior thigh. Histopathology reveals an undifferentiated pleomorphic sarcoma. When counseling the patient regarding his long-term prognosis, which of the following is considered the single most important prognostic factor for overall survival and the development of distant metastasis?

. Tumor size (> 5 cm)
. Tumor depth (superficial vs. deep to fascia)
. Histologic grade of the tumor
. Patient age at presentation
. Surgical margin status

Correct Answer & Explanation

. Histologic grade of the tumor

Explanation

In adult soft tissue sarcomas, the histologic grade (which incorporates differentiation, mitotic count, and percentage of necrosis) is the single most important prognostic factor for overall survival and the development of distant metastasis. While tumor size (> 5 cm) and tumor depth are important staging criteria that influence prognosis, grade remains the most significant independent predictor. Surgical margin status is the most important predictor of local recurrence but has less impact on overall survival than histologic grade.

Question 2908

Topic: 10. Pathology and Oncology

A 65-year-old man presents with progressive aching pain in his right shoulder. Radiographs show a large, ill-defined lytic lesion in the proximal humerus with intralesional 'popcorn' and 'ring-and-arc' calcifications. There is endosteal scalloping greater than two-thirds of the cortical thickness. Biopsy confirms an intermediate-grade conventional chondrosarcoma. What is the most appropriate primary treatment for this patient?

. Neoadjuvant chemotherapy followed by wide surgical resection
. Definitive radiation therapy
. Intralesional extended curettage and bone grafting
. Wide surgical resection
. Radiofrequency ablation

Correct Answer & Explanation

. Wide surgical resection

Explanation

The clinical and radiographic presentation indicates a primary conventional chondrosarcoma. Conventional chondrosarcomas are notoriously resistant to both chemotherapy and radiation therapy due to their poor vascularity, slow cellular division, and dense extracellular matrix. The absolute mainstay of treatment for intermediate- and high-grade conventional chondrosarcoma is wide surgical resection. Intralesional curettage may sometimes be utilized for low-grade (grade 1) chondrosarcomas in the long bones, but it is contraindicated for intermediate- or high-grade lesions.

Question 2909

Topic: 10. Pathology and Oncology

A 60-year-old woman with a history of lung cancer complains of moderate pain in her hip, particularly when weight-bearing. Radiographs reveal a purely lytic metastatic lesion in the peritrochanteric region of the proximal femur. The lesion occupies approximately 25% of the total cortical diameter. According to the Mirels scoring system, what is her calculated score, and what is the recommended management regarding surgical intervention?

. Score 7; prophylactic fixation is not indicated
. Score 8; prophylactic fixation is borderline and optional
. Score 9; prophylactic internal fixation is highly recommended
. Score 10; prophylactic internal fixation is highly recommended
. Score 11; prophylactic internal fixation is highly recommended

Correct Answer & Explanation

. Score 9; prophylactic internal fixation is highly recommended

Explanation

Mirels' criteria assess the risk of pathologic fracture using four categories, each scored from 1 to 3: Site (Upper extremity=1, Lower extremity=2, Peritrochanteric=3); Pain (Mild=1, Moderate=2, Severe/Functional=3); Lesion type (Blastic=1, Mixed=2, Lytic=3); and Size (<1/3=1, 1/3-2/3=2, >2/3=3). This patient scores: Site (peritrochanteric) = 3; Pain (moderate) = 2; Lesion (lytic) = 3; Size (<1/3) = 1. The total score is 3+2+3+1 = 9. A Mirels score of 9 or greater indicates a high risk for pathologic fracture (typically >15%), making prophylactic internal fixation highly recommended prior to beginning radiation therapy.

Question 2910

Topic: 10. Pathology and Oncology
A 16-year-old girl is diagnosed with a conventional high-grade osteosarcoma of the distal femur. She completes a 10-week course of neoadjuvant multidrug chemotherapy and subsequently undergoes limb-salvage surgery. Histopathologic analysis of the resected tumor is performed to assess tumor necrosis. Which of the following thresholds of tumor necrosis is the most widely accepted indicator of a 'good' histologic response to neoadjuvant chemotherapy?
. > 50%
. > 70%
. > 90%
. > 95%
. 100%

Correct Answer & Explanation

. > 90%

Explanation

In the treatment of conventional high-grade osteosarcoma, the degree of tumor necrosis following neoadjuvant chemotherapy is one of the most important prognostic factors for long-term survival. The most widely accepted threshold for a 'good response' is > 90% tumor necrosis (classified as Grade III or IV in the Huvos grading system). Patients demonstrating > 90% necrosis have significantly higher 5-year survival rates compared to poor responders (< 90% necrosis).

Question 2911

Topic: Bone Tumors

A 12-year-old boy presents with mild knee pain and swelling after a minor twist. Radiographs reveal an eccentric, expansile, lytic metaphyseal lesion in the proximal tibia. MRI demonstrates multiple fluid-fluid levels within the lesion. A biopsy confirms the diagnosis of a primary aneurysmal bone cyst (ABC). Which of the following genetic alterations is most specific to the pathogenesis of this lesion?

. GNAS mutation
. USP6 gene rearrangement
. EXT1 mutation
. p53 mutation
. BRAF V600E mutation

Correct Answer & Explanation

. USP6 gene rearrangement

Explanation

Primary aneurysmal bone cysts (ABCs) are true neoplastic processes driven by specific genetic rearrangements, most commonly involving the USP6 gene on chromosome 17p13. This translocation leads to the upregulation of USP6, a ubiquitin-specific protease, driving the formation of the cystic lesion. GNAS mutations are associated with fibrous dysplasia. EXT1 and EXT2 mutations cause hereditary multiple exostoses. BRAF V600E mutations are commonly associated with Langerhans cell histiocytosis and occasionally non-ossifying fibromas.

Question 2912

Topic: Bone Tumors

A 68-year-old man presents with generalized fatigue, severe lower back pain, and a recent laboratory finding of hypercalcemia. Radiographs show multiple punched-out lytic lesions in his skull and pelvis. Routine laboratory tests reveal a mild normocytic anemia and elevated serum creatinine. Which of the following tests is the most appropriate initial diagnostic step to confirm the suspected underlying malignancy?

. Whole-body technetium-99m bone scan
. Serum protein electrophoresis (SPEP) and immunofixation
. Serum alkaline phosphatase level
. Prostate-specific antigen (PSA) test
. Flow cytometry of the peripheral blood

Correct Answer & Explanation

. Serum protein electrophoresis (SPEP) and immunofixation

Explanation

The patient's presentation of hypercalcemia, renal dysfunction (elevated creatinine), anemia, and lytic bone lesions comprises the classic 'CRAB' criteria for multiple myeloma. To confirm the diagnosis, identifying and quantifying the monoclonal protein (M-spike) is essential. Serum protein electrophoresis (SPEP) with immunofixation, along with urine protein electrophoresis (UPEP), is the most appropriate diagnostic step. Technetium-99m bone scans rely on osteoblastic activity and often yield false-negative results in multiple myeloma, which is characterized by purely osteoclastic bone destruction. Low-dose whole-body CT, MRI, or PET-CT are the preferred imaging modalities.

Question 2913

Topic: 10. Pathology and Oncology

A 19-year-old college student presents with right thigh pain that has been present for 4 months. The pain is described as a deep, dull ache that is significantly worse at night and is completely relieved within 30 minutes of taking ibuprofen. A CT scan shows a 7-mm radiolucent nidus surrounded by dense sclerotic bone in the femoral diaphysis. The dramatic relief of pain with nonsteroidal anti-inflammatory drugs (NSAIDs) is primarily due to the high concentration of which of the following substances within the tumor nidus?

. Interleukin-1 (IL-1)
. Prostaglandin E2 (PGE2)
. Tumor necrosis factor-alpha (TNF-alpha)
. Substance P
. Bradykinin

Correct Answer & Explanation

. Prostaglandin E2 (PGE2)

Explanation

The clinical presentation is classic for an osteoid osteoma, a benign bone-forming tumor characterized by nocturnal pain relieved by NSAIDs. The tumor nidus produces extremely high levels of prostaglandins, particularly Prostaglandin E2 (PGE2), sometimes at concentrations 100 to 1000 times higher than in normal tissue. PGE2 causes intense local vasodilation and lowers the pain threshold of local sensory nerve fibers. NSAIDs inhibit cyclooxygenase (COX), effectively halting prostaglandin synthesis and providing rapid, profound pain relief.

Question 2914

Topic: 10. Pathology and Oncology

A 62-year-old man with a history of a radical nephrectomy 5 years ago presents with an impending pathologic fracture of his right humerus. Radiographs show a large, expansile, purely lytic lesion in the humeral diaphysis. Surgical stabilization with an intramedullary nail and lesional curettage is planned. Given the most likely primary malignancy, which of the following complications must the orthopedic surgeon be specifically prepared for during the surgical intervention?

. Severe systemic hypercalcemia upon tumor manipulation
. A densely sclerotic bone response preventing nail passage
. Massive intraoperative hemorrhage
. Spontaneous tumor fragmentation causing diffuse fat embolism
. Severe hypotension secondary to catecholamine release

Correct Answer & Explanation

. Massive intraoperative hemorrhage

Explanation

The patient has a metastatic lesion from renal cell carcinoma (RCC). Both RCC and thyroid carcinoma are known to produce highly vascular, osteolytic bone metastases. These metastases can lead to massive, potentially life-threatening intraoperative hemorrhage during surgical stabilization or resection. Due to this significant risk, preoperative selective arterial embolization of the tumor is strongly recommended 24 to 48 hours prior to orthopedic surgical intervention.

Question 2915

Topic: 10. Pathology and Oncology

A 45-year-old man presents with a painless, deep, 8-cm soft-tissue mass in his thigh. Core needle biopsy confirms a high-grade pleomorphic sarcoma. Which of the following is the most appropriate imaging study to evaluate for the most common site of metastasis in this patient?

. Technetium-99m bone scan
. Non-contrast CT of the chest
. CT of the abdomen and pelvis
. MRI of the brain
. PET scan

Correct Answer & Explanation

. Non-contrast CT of the chest

Explanation

The most common site of distant metastasis for the majority of soft-tissue sarcomas of the extremities is the lungs. Therefore, a non-contrast CT of the chest is the most appropriate and sensitive imaging study for initial staging to rule out pulmonary metastases.

Question 2916

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a painful, swollen thigh. A representative radiograph is shown below.

It demonstrates a permeative, diaphyseal lesion in the femur with an 'onion-skin' periosteal reaction. A core needle biopsy is performed. Which of the following chromosomal translocations is most characteristic of this patient's likely diagnosis?

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

Correct Answer & Explanation

. t(11;22)

Explanation

The clinical and radiographic findings describe Ewing sarcoma. Ewing sarcoma is classically associated with the t(11;22)(q24;q12) chromosomal translocation, which results in the EWS-FLI1 fusion protein. This occurs in approximately 85% to 90% of cases. t(X;18) is seen in synovial sarcoma, t(12;16) in myxoid liposarcoma, and t(2;13) in alveolar rhabdomyosarcoma.

Question 2917

Topic: 10. Pathology and Oncology

A 55-year-old man presents with progressive aching pain in his right shoulder. Radiographs show a large, ill-defined lytic lesion in the proximal humerus with intralesional 'popcorn' calcifications and endosteal scalloping greater than two-thirds of the cortical thickness. Biopsy confirms a grade 2 conventional chondrosarcoma. What is the most appropriate definitive management?

. Intralesional curettage and bone grafting
. Neoadjuvant chemotherapy followed by wide surgical resection
. Wide surgical resection alone
. Definitive radiation therapy
. Radiofrequency ablation

Correct Answer & Explanation

. Wide surgical resection alone

Explanation

Conventional chondrosarcomas (especially grades 2 and 3) are typically resistant to both chemotherapy and radiation therapy due to their poor vascularity and slow growth rate. Therefore, the mainstay of treatment for a grade 2 chondrosarcoma is wide surgical resection alone to achieve negative margins.

Question 2918

Topic: Bone Tumors

A 19-year-old man presents with a 6-month history of right thigh pain that is worse at night and relieved significantly by ibuprofen. A CT scan of the femur is shown below.

It reveals a 7-mm radiolucent nidus surrounded by dense sclerotic bone in the femoral diaphysis. If a molecular analysis of the resected tissue were performed, the lesion would most likely demonstrate high levels of which of the following?

. Interleukin-6 (IL-6)
. Tumor necrosis factor-alpha (TNF-alpha)
. Cyclooxygenase-2 (COX-2)
. Vascular endothelial growth factor (VEGF)
. Fibroblast growth factor receptor 3 (FGFR3)

Correct Answer & Explanation

. Cyclooxygenase-2 (COX-2)

Explanation

The presentation is classic for an osteoid osteoma. Osteoid osteomas characteristically secrete high levels of prostaglandins, mediated by robust expression of cyclooxygenase-2 (COX-2) within the nidus. This accounts for the intense, night-predominant pain that typically responds dramatically to NSAIDs or salicylates.

Question 2919

Topic: 10. Pathology and Oncology

A 65-year-old man presents with generalized bone pain and a newly discovered lytic lesion in the proximal femur. Laboratory studies show anemia, hypercalcemia, and renal insufficiency. A diagnosis of multiple myeloma is suspected. Which of the following imaging modalities is the most sensitive and appropriate for assessing the full extent of skeletal tumor burden in this patient?

. Whole-body MRI
. Technetium-99m bone scan
. Ultrasound of the abdomen
. Standard anterior-posterior radiographs of the appendicular skeleton only
. DEXA scan

Correct Answer & Explanation

. Whole-body MRI

Explanation

The patient's presentation fits the CRAB criteria (hyperCalcemia, Renal failure, Anemia, Bone lesions) highly suggestive of multiple myeloma. Whole-body MRI or low-dose whole-body CT are currently the modalities of choice for assessing skeletal involvement, as they are highly sensitive for detecting marrow replacing lesions. Technetium-99m bone scans are notoriously insensitive for myeloma because the lesions are purely lytic and lack the osteoblastic response required for tracer uptake.

Question 2920

Topic: 10. Pathology and Oncology

A 68-year-old man with a long-standing history of Paget disease of bone presents with acutely worsening, severe pain in his left thigh and a newly palpable mass. Radiographs reveal a destructive lytic lesion with cortical breakthrough in the proximal femur, located within an area of thickened, sclerotic Pagetoid bone. What is the most likely diagnosis of this new lesion?

. Metastatic prostate carcinoma
. Secondary osteosarcoma
. Multiple myeloma
. Chondrosarcoma
. Malignant fibrous histiocytoma

Correct Answer & Explanation

. Secondary osteosarcoma

Explanation

In an older patient with known Paget disease of bone who presents with an acute onset of severe pain, a new mass, and aggressive bone destruction, secondary malignant transformation must be highly suspected. Osteosarcoma is the most common sarcoma to arise in Paget disease (Pagetoid osteosarcoma), occurring in roughly 1% of affected patients. It carries a notoriously poor prognosis.

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