Peptide-hormone- and serotonin-immunoreactive tumour cells in carcinoma of the prostate.

In order to establish the extent of neuroendocrine differentiation and the occurrence of neurohormonal peptides in the neoplastic cells of prostatic carcinomas, silver-staining and immunocytochemical techniques were used. All gave satisfactory results. The incidence of the neuroendocrine cells seemed to be higher in the fresh "Bouin-fixed" biopsy specimens than in the conventionally "formalin-fixed" specimens from archival paraffin blocks. All carcinomas demonstrated argyrophil cells as an integral element of the tumour. In highly differentiated carcinomas (grade I) these cells were scattered focally, intermingled with non-argyrophil cells in typical adenocarcinomas; their incidence was estimated to be about the same as in benign prostatic hyperplasia. Most of them were immunoreactive with antisera raised against serotonin and/or TSH (thyroid stimulating hormone). In moderately and poorly differentiated (grades II-III) carcinomas, however, the argyrophil cells were more numerous and showed greater variation in growth pattern; only occasionally they displayed a typical carcinoid-like structure. Moderately and poorly differentiated carcinomas also showed a greater variation in the number and kinds of peptide immunoreactivities than the highly differentiated carcinomas. In addition to serotonin- and TSH-immunoreactive cells as the most prevalent type, now also human chorionic gonadotrophin (HCG-alpha), adrenocorticotropic hormone (ACTH), leu-enkephalin, beta-endorphin, somatostatin, glucagon and calcitonin immunoreactive cells could be found within certain tumour areas and often with a distinctly patchy distribution. In two cases, where the tumour cells in the metastases were also investigated, they were found to be both argyrophil and immunoreactive with the same antisera as those of the primary tumour. Our findings emphasise the fact that prostatic carcinomas are more complex and heterogenous than previously thought, exhibiting endocrine differentiation as an integral element of virtually all prostatic adenocarcinomas.