Cytopathology in focus: Navigating papillary lesions in Lynch syndrome
August 2025—Case summary. A 52-year-old chronic smoker with a known MLH1 mutation and Lynch syndrome presented with a pleural-based lung lesion. Fine-needle aspiration revealed a malignant neoplasm with papillary architecture, featuring enlarged overlapping nuclei, coarse chromatin, prominent nucleoli, and rare mitotic figures. Given the patient’s clinical background and cytologic findings, a broad differential diagnosis including primary and metastatic tumors from both thoracic and ab-dominal origins was considered.