Neoplasia USMLE Step 1 Practice Question
A 62-year-old man with a 40-pack-year smoking history presents to the emergency department with hemoptysis and dyspnea. Chest X-ray shows a central lung mass with post-obstructive pneumonia. Bronchoscopy reveals a polypoid lesion obstructing the left mainstem bronchus with friable, bleeding tissue. Biopsy demonstrates small, round cells with scant cytoplasm, dense chromatin, and frequent mitotic figures. Immunohistochemistry is positive for synaptophysin and CD56. Which of the following is the most likely diagnosis?
Answer choices
- ATypical carcinoid tumor (low-grade neuroendocrine carcinoma)
- BLarge cell neuroendocrine carcinoma
- CSquamous cell carcinoma of the lung
- DAdenocarcinoma with neuroendocrine differentiation
- ESmall cell lung cancerCorrect answer
- FAtypical carcinoid tumor (intermediate-grade neuroendocrine carcinoma)
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