PROSTATIC MARKER-NEGATIVE AMPHICRINE CARCINOMA OF THE PROSTATE

It has been shown that prostatic adenocarcinoma differentiation correl ates with prostatic-specific marker and neuroendocrine expression; tha t is, the more undifferentiated the tumor, the less it expresses prost atic markers and the more neuroendocrine cells are found in it. Comple te absence of prostatic markers together with marked neuroendocrine ex pression has been associated with small cell morphology. This report d escribes a case of a metastatic, prostatic marker-negative, non-small cell prostatic adenocarcinoma with a prominent neuroendocrine componen t. The architecturally well-organized luminal-exocrine cells appeared ultrastructurally undifferentiated, however, displaying an almost empt y cytoplasm. This contrasted with the prostatic marker-positive contro l cases of prostatic carcinoma, which contained relatively numerous cy toplasmic vacuoles. The neuroendocrine cells could be identified by li ght microscopy as eosinophilic cells. The number of the latter cells w as markedly increased in the metastatic foci compared with the primary tumor. Light microscopially and ultrastructurally, the eosinophilic c ells in this case differed from the Paneth-like cells described in pro static carcinoma in previous reports. This case provides support for t he general concept of multidirectional differentiation in human epithe lial cancers and in particular for the association of poor tumor diffe rentiation with neuroendocrine expression in prostatic carcinoma. In a ddition, in contrast with previous reports describing absence of basem ent membrane in metastatic foci of prostatic carcinoma, in the current case well-formed basal laminae were identified.