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10. Pathology and Oncology MCQs

Practice Set 155 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 3081

Topic: 10. Pathology and Oncology

A 55-year-old male presents with generalized weakness and nephrolithiasis. Radiographs reveal a lytic bone lesion. Biopsy shows abundant giant cells, hemosiderin-laden macrophages, and a background of spindle cells.

What is the most likely serum laboratory profile for this patient?

. High Calcium, Low Phosphate, High Parathyroid Hormone
. Normal Calcium, High Phosphate, High Parathyroid Hormone
. Low Calcium, Low Phosphate, High Parathyroid Hormone
. Normal Calcium, Normal Phosphate, Normal Parathyroid Hormone

Correct Answer & Explanation

. High Calcium, Low Phosphate, High Parathyroid Hormone

Explanation

The clinical presentation and biopsy describe a 'Brown tumor' (osteitis fibrosa cystica), a hallmark of primary hyperparathyroidism. This condition, typically caused by a parathyroid adenoma, presents with hypercalcemia, hypophosphatemia, and elevated parathyroid hormone.

Question 3082

Topic: 10. Pathology and Oncology

Aspiration of an acutely inflamed metatarsophalangeal joint in a 45-year-old male yields fluid with 25,000 WBCs/mcL, predominantly consisting of a specific inflammatory cell. The inflammation is heavily driven by the NLRP3 inflammasome. Which cell type and cytokine are primarily driving this acute gouty inflammation?

. Lymphocytes and Interleukin-2
. Macrophages and Tumor Necrosis Factor-alpha
. Neutrophils and Interleukin-1 beta
. Eosinophils and Interleukin-5

Correct Answer & Explanation

. Neutrophils and Interleukin-1 beta

Explanation

Monosodium urate crystals are phagocytosed by macrophages, activating the NLRP3 inflammasome to produce large amounts of IL-1 beta. This potent cytokine triggers a massive influx of neutrophils, which make up the vast majority of cells in acute gouty synovial fluid.

Question 3083

Topic: 10. Pathology and Oncology

A 65-year-old man with a known history of Paget's disease presents with a new onset of severe, unrelenting thigh pain and swelling over the past two months. Radiographs reveal a new, destructive lytic lesion in the femur with cortical breakthrough. What is the most likely diagnosis?

. Chondrosarcoma
. Osteosarcoma
. Multiple Myeloma
. Metastatic prostate cancer
. Ewing sarcoma

Correct Answer & Explanation

. Osteosarcoma

Explanation

Osteosarcoma is the most common secondary malignancy arising in Paget's disease, typically presenting with new severe pain and a destructive bone lesion. The incidence is roughly 1% in patients with Paget's, but it carries a very poor prognosis.

Question 3084

Topic: 10. Pathology and Oncology

A patient with secondary hyperparathyroidism presents with a well-demarcated lytic bone lesion in the distal radius. A biopsy is performed. Which histological description best characterizes a Brown tumor?

. Atypical chondrocytes with binucleation and myxoid stroma
. Sheets of small round blue cells with Homer-Wright rosettes
. Multinucleated giant cells scattered in a highly vascularized cellular fibrous stroma
. Nests of epithelial cells with prominent keratin pearls
. Acellular woven bone trabeculae surrounded by dense connective tissue

Correct Answer & Explanation

. Multinucleated giant cells scattered in a highly vascularized cellular fibrous stroma

Explanation

A Brown tumor of hyperparathyroidism is a localized accumulation of fibrous tissue, blood, and multinucleated giant cells resulting from intense osteoclastic activity. Histologically, it is virtually indistinguishable from a true giant cell tumor of bone.

Question 3085

Topic: 10. Pathology and Oncology

A 72-year-old man with a long history of Paget's disease presents with a 2-month history of worsening, unrelenting right thigh pain and a newly palpable mass. Radiographs reveal a destructive lytic lesion with cortical breakthrough in the mid-diaphysis of his thickened, bowed right femur. Which of the following is the most likely diagnosis?

. Chondrosarcoma
. Metastatic prostate carcinoma
. Osteosarcoma
. Multiple myeloma
. Giant cell tumor of bone

Correct Answer & Explanation

. Osteosarcoma

Explanation

Secondary osteosarcoma is a rare but highly lethal complication of Paget's disease, affecting roughly 1% of patients and presenting with new-onset, unrelenting bone pain. It arises in polyostotic disease and has a very poor prognosis compared to primary osteosarcoma.

Question 3086

Topic: 10. Pathology and Oncology

A 40-year-old woman presents with a pathologic fracture of her left humerus. A radiograph reveals a lytic, expansile lesion. Biopsy shows clusters of multinucleated giant cells within a highly vascular, hemorrhagic stroma containing hemosiderin-laden macrophages.

Which of the following tests is most critical to confirm the underlying etiology?

. Serum protein electrophoresis
. Serum parathyroid hormone level
. Urinary N-telopeptide
. Serum uric acid level
. Flow cytometry

Correct Answer & Explanation

. Serum parathyroid hormone level

Explanation

The histological and radiographic findings describe a Brown tumor (osteitis fibrosa cystica), which is highly associated with hyperparathyroidism. Evaluating serum parathyroid hormone and calcium levels is critical to differentiate a Brown tumor from a true giant cell tumor of bone.

Question 3087

Topic: 10. Pathology and Oncology

A 45-year-old woman with end-stage renal disease presents with a painful lytic lesion in her proximal tibia. Laboratory tests reveal significantly elevated parathyroid hormone (PTH) and low serum calcium. A biopsy of the lesion is performed. What is the characteristic histological finding expected in this lesion?

. Sheets of atypical plasma cells with eccentric nuclei
. Nests of epithelioid cells within a loose myxoid stroma
. Accumulation of hemosiderin-laden macrophages and multinucleated giant cells
. Disorganized woven bone with a mosaic pattern of cement lines
. Negatively birefringent needle-shaped crystals

Correct Answer & Explanation

. Accumulation of hemosiderin-laden macrophages and multinucleated giant cells

Explanation

The patient has a Brown tumor, a classic bone lesion associated with severe hyperparathyroidism (osteitis fibrosa cystica). Histologically, Brown tumors consist of highly vascularized fibrous tissue with accumulations of hemosiderin-laden macrophages, multinucleated giant cells, and microhemorrhages.

Question 3088

Topic: 10. Pathology and Oncology

A 76-year-old man with a long-standing history of Paget's disease involving his pelvis presents with severe, progressive, and unremitting left hip pain over the past 2 months. Recent radiographs demonstrate a new destructive, permeative lytic lesion with cortical breakthrough. What is the most likely diagnosis for this new lesion?

. Chondrosarcoma
. Osteosarcoma
. Ewing sarcoma
. Multiple myeloma
. Metastatic prostate cancer

Correct Answer & Explanation

. Osteosarcoma

Explanation

Malignant transformation is a rare but lethal complication of Paget's disease, occurring in roughly 1% of patients. Secondary osteosarcoma is the most common histological subtype, presenting with new-onset, severe, and relentless pain along with destructive radiographic changes.

Question 3089

Topic: 10. Pathology and Oncology

A 72-year-old man with known Paget's disease of the right femur presents with acutely worsening, severe right thigh pain that wakes him up at night. Radiographs demonstrate a new, destructive, lytic lesion breaking through the cortex. What is the most likely diagnosis?

. Chondrosarcoma
. Ewing sarcoma
. Osteosarcoma
. Multiple myeloma
. Metastatic prostate cancer

Correct Answer & Explanation

. Osteosarcoma

Explanation

The most dreaded complication of Paget's disease is malignant transformation, which occurs in roughly 1% of patients. Secondary osteosarcoma is the most common histological type, presenting with acute, severe pain and a destructive bone lesion in a previously pagetic bone.

Question 3090

Topic: Bone Tumors
A 7-year-old girl presents with a limp, precocious puberty, and large, irregular, hyperpigmented skin macules. Radiographs of the right femur show an expansile, radiolucent lesion with a "ground-glass" appearance. Which of the following describes the underlying genetic pathogenesis?
. Germline mutation in FGFR3
. Postzygotic somatic mutation in the GNAS gene
. Autosomal recessive mutation in TCIRG1
. Deletion on chromosome 15q
. Mutation in the NF1 gene

Correct Answer & Explanation

. Postzygotic somatic mutation in the GNAS gene

Explanation

McCune-Albright syndrome consists of polyostotic fibrous dysplasia, precocious puberty, and café-au-lait spots with rough "coast of Maine" borders. It is caused by a postzygotic somatic (mosaic) activating mutation in the GNAS gene.

Question 3091

Topic: 10. Pathology and Oncology

A 15-year-old boy is diagnosed with high-grade conventional osteosarcoma of the distal femur. After completing a course of neoadjuvant chemotherapy, he undergoes wide surgical resection. Which of the following is the most important prognostic factor for his long-term survival?

. Tumor size at the time of presentation
. Histologic subtype (osteoblastic vs. chondroblastic)
. Percentage of tumor necrosis in the resected specimen
. Level of serum alkaline phosphatase pre-operatively
. Proximity to the physis

Correct Answer & Explanation

. Percentage of tumor necrosis in the resected specimen

Explanation

The most critical prognostic factor for localized osteosarcoma is the histologic response to neoadjuvant chemotherapy. Greater than 90% tumor necrosis in the resected specimen is considered a good response and correlates with improved overall survival.

Question 3092

Topic: 10. Pathology and Oncology

A 12-year-old girl presents with a painful, swollen thigh and systemic symptoms including fever. Biopsy reveals small round blue cells expressing CD99. Which of the following chromosomal translocations is most characteristic of this lesion?

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

Correct Answer & Explanation

. t(11;22)

Explanation

Ewing sarcoma is a small round blue cell tumor typically characterized by the t(11;22)(q24;q12) translocation, resulting in the EWS-FLI1 fusion protein. CD99 (MIC2) is strongly positive on immunohistochemistry.

Question 3093

Topic: 10. Pathology and Oncology
A 55-year-old man presents with deep thigh pain. Imaging reveals a large, lobulated medullary lesion in the proximal femur with "rings and arcs" calcification. Biopsy confirms a grade II chondrosarcoma. What is the most appropriate management?
. Intralesional curettage with bone grafting
. Wide surgical resection
. Neoadjuvant chemotherapy followed by resection
. Primary radiation therapy
. Radiofrequency ablation

Correct Answer & Explanation

. Wide surgical resection

Explanation

Grade II and III chondrosarcomas require wide surgical resection because they are largely resistant to conventional chemotherapy and radiation. Intralesional curettage is reserved for grade I (atypical cartilaginous tumors) in the appendicular skeleton.

Question 3094

Topic: Bone Tumors

A 19-year-old male complains of right thigh pain that is worse at night and dramatically improves with ibuprofen. A CT scan reveals a 7-mm radiolucent nidus surrounded by dense sclerotic bone in the femoral diaphysis. What is the most appropriate definitive treatment?

. Wide surgical excision
. Intralesional steroid injection
. Radiofrequency ablation
. 6 weeks of intravenous antibiotics
. External beam radiation

Correct Answer & Explanation

. Radiofrequency ablation

Explanation

Osteoid osteoma classically presents with nocturnal pain relieved by NSAIDs due to high prostaglandin production by the nidus. Radiofrequency ablation (RFA) is the current gold standard definitive treatment, offering high success rates with minimal morbidity.

Question 3095

Topic: Bone Tumors
A 10-year-old girl is evaluated for a shepherd's crook deformity of her proximal femur. Radiographs show a "ground-glass" appearance of the medullary canal. She also has precocious puberty and large café-au-lait macules with irregular borders. What is the underlying genetic mutation?
. NF1
. COL1A1
. FGFR3
. GNAS1
. RUNX2

Correct Answer & Explanation

. GNAS1

Explanation

McCune-Albright syndrome consists of polyostotic fibrous dysplasia, café-au-lait spots with irregular "coast of Maine" borders, and endocrine abnormalities. It is caused by a somatic activating mutation in the GNAS1 gene, which increases intracellular cAMP.

Question 3096

Topic: Bone Tumors
A 65-year-old man presents with persistent back pain and fatigue. Blood tests reveal anemia, hypercalcemia, and an elevated creatinine. A serum protein electrophoresis demonstrates a monoclonal spike. Which imaging modality is most sensitive for detecting early impending pathologic fractures in this patient's long bones?
. Technetium-99m bone scan
. Standard skeletal survey (plain radiographs)
. Whole-body low-dose CT (WBLDCT)
. Positron emission tomography (PET)
. Diagnostic ultrasound

Correct Answer & Explanation

. Whole-body low-dose CT (WBLDCT)

Explanation

Multiple myeloma often results in purely lytic bone lesions that may not be active on a traditional Technetium-99m bone scan due to lack of osteoblastic response. Whole-body low-dose CT or MRI is currently favored over standard skeletal surveys for superior sensitivity in detecting lytic lesions.

Question 3097

Topic: 10. Pathology and Oncology
A 58-year-old woman with a history of breast cancer presents with left hip pain. Radiographs demonstrate a 3.5 cm lytic lesion in the peritrochanteric region of the left femur, involving >50% of the cortex. She reports pain with weight-bearing. According to Mirels' criteria, what is the most appropriate management?
. Protected weight-bearing and bisphosphonate therapy
. External beam radiation therapy alone
. Prophylactic internal fixation followed by radiation therapy
. Neoadjuvant chemotherapy
. Radiofrequency ablation

Correct Answer & Explanation

. Prophylactic internal fixation followed by radiation therapy

Explanation

This patient has a Mirels' score of at least 10 (Site: lower limb=3, Pain: functional/weight-bearing=3, Lesion: lytic=3, Size: >2/3 cortex=3). A score >8 indicates a high risk of impending pathologic fracture, necessitating prophylactic internal fixation followed by local radiation.

Question 3098

Topic: 10. Pathology and Oncology

A 72-year-old man with known long-standing Paget's disease of the pelvis presents with a rapid increase in localized pain over the right ilium and a new palpable mass. Laboratory studies show a sudden exponential rise in serum alkaline phosphatase. What is the most likely diagnosis?

. Secondary osteosarcoma
. Chondrosarcoma
. Metastatic prostate cancer
. Osteomyelitis
. Giant cell tumor of bone

Correct Answer & Explanation

. Secondary osteosarcoma

Explanation

Sarcomatous degeneration (usually into osteosarcoma) is a rare but highly lethal complication of Paget's disease, occurring in <1% of patients. It should be suspected when a patient with Paget's disease develops sudden worsening pain, a new mass, or an exponential rise in alkaline phosphatase.

Question 3099

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a painful, swollen thigh and low-grade fever. Radiographs show a permeative, diaphyseal lesion with an "onion-skin" periosteal reaction. Which chromosomal translocation is most characteristic of this malignancy?

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

Correct Answer & Explanation

. t(11;22)

Explanation

Ewing sarcoma typically presents in the diaphysis with a permeative pattern and "onion-skinning." It is classically associated with the t(11;22) translocation, which creates the EWS-FLI1 fusion oncogene.

Question 3100

Topic: 10. Pathology and Oncology

A 16-year-old girl has a destructive metaphyseal lesion in the proximal tibia accompanied by a "sunburst" periosteal reaction. A core needle biopsy confirms high-grade conventional osteosarcoma. Following neoadjuvant chemotherapy and surgical resection, what is the most critical prognostic factor for her long-term survival?

. Tumor size at initial presentation
. Percentage of tumor necrosis found in the resection specimen
. Presence of a Codman triangle on initial radiographs
. Preoperative alkaline phosphatase level
. The specific histological subtype (e.g., osteoblastic vs. chondroblastic)

Correct Answer & Explanation

. Percentage of tumor necrosis found in the resection specimen

Explanation

The degree of tumor necrosis after neoadjuvant chemotherapy is the single most important prognostic factor for survival in osteosarcoma. Greater than 90% necrosis defines a good responder and portends a better prognosis.

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