Nuclear DNA record in a malignant rectal carcinoid. A case report.

A colo-rectal resection was performed on a 73-year-old woman with a preoperative diagnosis of rectal carcinoma. Morphological examination of the specimen revealed a rectal carcinoid tumor with regional lymph node and liver metastases. Silver stains demonstrated an argyrophil reaction in the tumor cells, but the argentaffin reaction and immunocytochemistry with monoclonal serotonin antibodies were negative. Imprint cytology of the tumor was examined cytofluorometrically and diploid nuclear DNA values were recorded with only few tetraploid cells (less than 2%.). It is suggested that diploid nuclear DNA values and a low proliferative activity are characteristic of malignant rectal carcinoids.