Flow cytometric DNA analysis of anal canal epithelium and ano-rectal tumours.

Flow cytometric DNA analysis was performed on mucosal biopsies from the various epithelial types normally present in the anal canal, i.e. colo-rectal epithelium, ATZ-epithelium and squamous epithelium as well as from rectal and anal adenocarcinomas and squamous carcinomas of the anal canal. Normal colo-rectal mucosa show homogeneous cell populations with diploid DNA values, while adenocarcinomas contain diploid as well as aneuploid cell populations, regardless of location in the rectum or in the anal canal. The ATZ-epithelium shows a dominating normoploid population with a small "hyperdiploid" peak. Polyploid nuclei were not found. The findings indicate that the ATZ-epithelium is related to metaplastic epithelium rather than to urothelium. The variants of squamous carcinoma in this study were rather poorly differentiated, but the FCM-analysis showed a near diploid population with a high proliferative activity. The number of cases, however, is too small to be conclusive.