The authors presented and unusual mixed carcinoid-adebicarcubina of the prostate with in situ and invasive components. The carcinoid tumor showed various architectural patterns including prominent multifocal spindle cell differentiation. Spindle cell carcinoid turnor is a recognized variant in other sites, but has not, to the best of the authors knowledge, been described in the prostate. The tumor expressed markers of neuroendocrne differentiation (chromogranin, neuron-specific enolase) as well as prostate-specific antigen adn prostatie acid phosphatase. In addition, there was an in situ component with histologic and immunohistochemical features of neuroendocrine differntiation. Although neuroendocrine differentiation has been documented in prostatic intraepithelial neoplasia, there have been no reports fo in situ neuroendocrine carcinoma. This unusual tumor expands the known spectrum of neuroendocrine differentiation in prostatic neoplasia.