Multiple malignant rectal carcinoid tumors with immunocytochemical demonstration of multiple hormonal substances.

This case report deals with a patient who presented with 17 small carcinoid tumors of the rectum, the largest measuring less than 1 cm in diameter. After a review of the literature on this subject, this case is believed to be highly unusual in several respects: (1) despite their small size, these tumors resulted in multiple metastases to the regional lymph nodes; (2) both primary tumors and metastases were extensively and strongly argentaffin; and (3) most tumors and metastases contained, when investigated by immunocytochemistry, several biologically active substances such as serotonin, somatostatin, and glucagon-like immunoreactivity.