Endocrine cells in colorectal carcinomas. Immunohistochemical study.

Immunostaining for chromogranin A, serotonin, glucagon and somatostatin revealed the presence of endocrine cells in 20 (35.1%) out of 57 randomly selected colorectal carcinomas. Expression of a general "neuroendocrine" marker, chromogranin A was detected in 18 tumours, whereas in the remaining two carcinomas positive reactivity with glucagon only was seen. Serotonin was expressed in 9 carcinomas, glucagon in 5 and somatostatin in 4 carcinomas. In 3 tumours coexpression of active products was found: in one--serotonin and glucagon, in another--serotonin and somatostatin, and in the last one--serotonin, glucagon and somatostatin. In 6 carcinomas expressing chromogranin A there was no expression of active products. Twelve carcinomas were assigned to a group with a small number of endocrine cells (up to 50/cm2 of tumour cross sectional area), 6 to a group with an intermediate number of endocrine cells (over 50 to 500/cm2) and 2 to a group with a large number of endocrine cells (over 500/cm2). The endocrine cells were significantly more frequent in less advanced and better differentiated carcinomas and in neoplasms with abundant mucin production. The cells were an integral part of glandular structures of the carcinoma, which argues in favour of a unitarian theory, i.e. common, endodermal origin of endocrine cells and other cellular elements of intestinal epithelium.