Organ System Pathology USMLE Step 1 Practice Question
A 62-year-old man with a 40-year smoking history presents to the emergency department with hemoptysis, chest pain, and progressive dyspnea over 3 weeks. He reports unintentional weight loss of 8 kg over 2 months. Vital signs reveal BP 138/82 mmHg, HR 102/min, RR 22/min. Chest X-ray shows a 3-cm central hilar mass with mediastinal widening. Bronchoscopy reveals an endobronchial lesion, and tissue biopsy demonstrates sheets of cells with scant cytoplasm, round to oval hyperchromatic nuclei with "molded" appearance, numerous mitotic figures, and extensive necrosis. Immunohistochemistry is positive for chromogranin A and synaptophysin. Which of the following best describes the histologic classification and key pathologic features of this malignancy?
Answer choices
- ASmall cell lung carcinoma with neuroendocrine differentiationCorrect answer
- BSquamous cell carcinoma with central keratinization and intercellular bridges
- CLarge cell neuroendocrine carcinoma with Ki-67 >30%
- DAdenocarcinoma with bronchioloalveolar pattern and mucin production
- ETypical pulmonary carcinoid (neuroendocrine tumor) with low mitotic rate
- FMixed adenosquamous carcinoma with both glandular and squamous components
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