Diagnosis of high-grade pulmonary neuroendocrine carcinoma by fine-needle aspiration biopsy: Nonsmall-cell or small-cell type?

A consensus optimal therapy for large‐cell neuroendocrine carcinoma of the lung has not been achieved since this entity was proposed in 1991. Accumulation of clinical data and investigation, however, can be greatly impeded by erroneous cytological diagnosis, based on which treatment may be initiated. To avoid erroneous diagnoses, cytological criteria need to be defined. Twenty cases of fine‐needle aspiration specimens with a diagnosis of neuroendocrine tumor by either cytology or follow‐up histology were retrospectively reviewed for cytomorphologic features. Patients' clinical data were also reviewed. Three cytomorphologic patterns were identified for large‐cell neuroendocrine carcinoma, i.e., nonsmall‐cell‐like, small‐cell‐like and, mixed nonsmall‐cell‐small‐cell‐like. Small‐cell‐like large‐cell neuroendocrine carcinoma can be mistaken for small‐cell carcinoma. The most important differential features between these two entities are nuclear size and perceptibility of nucleoli of tumor cells. Diagn. Cytopathol. 25:292–300, 2001. © 2001 Wiley‐Liss, Inc.