Large-cell neuroendocrine carcinoma of the lung: Proposed criteria for cytologic diagnosis

The category of large-cell neuroendocrine carcinoma (LCNEC) of the lung, pr oposed To expand the traditional scheme of typical carcinoid, atypical carc inoid (AC), and small-cell carcinoma (SCC), based on histologic features, h as not been defined in cytology. We attempt to describe LCNEC cytologically . Cytologic features in 16 histologically confirmed LCNECs in fine-needle a spiration biopsies, cell blocks, bronchial brushes, washes, and sputum spec imens stained with Diff-Quik, Papanicolaou, hematoxylin-eosin, chromogranin , and synaptophysin were analyzed. Three poorly differentiated nonsmall-cel l carcinomas, 4 SCCs, and 2 atypical carcinoids were studied similarly. Twe nty specimens from 16 histologically confirmed cases of LCNEC with original cytologic diagnoses including high-grade neuroendocrine carcinoma, large-c ell carcinoma, nonsmall-cell carcinoma, poorly differentiated carcinoma, ad enocarcinoma, and SCC, were examined. Features included flattened three-dim ensional clusters with peripheral palisading, moderate to large single cell s with scant (alcohol-fixed) or moderate (air-dried) cytoplasm; and large, oval, or polygonal nuclei with irregular contours, thickened nuclear membra nes, and finely or coarsely granular chromatin, showing some molding and cr ush artifact Nucleoli were generally present, and occasionally prominent. M itosis and necrosis were apparent. Neuroendocrine stains were applied to al l specimens, with at least one marker; commonly synaptophysin, positive in 18/20 specimens. LCNEC can be diagnosed in cytologic material, using morpho logy confirmed by immunocytochemistry. Treatment can be offered on the basi s of cytologic examination. (C) 2001 Wiley-Liss, Inc.