Apoptosis in flat neoplasias of the colorectal mucosa.

Intraepithelial and intramacrophageal inclusion granules (Leutchenberger bodies) were found in 83.9% of 174 flat neoplastic lesions of the colorectal mucosa. Flat adenomas with high grade dysplasia and flat adenocarcinomas originating in flat adenomas demonstrated a higher proportion of moderate to large (++/ ) numbers of granules than flat adenomas with low grade dysplasia, indicating that the occurrence of apoptotic granules may be related to the "biological age" of the adenoma. Early studies suggest that these inclusions may be the remains of intraepithelial lymphocytes. A lymphoid follicle aggre-gate subjacent to flat adenomas was recorded in 38% of the cases. Whether the intraepithelial lymphocytes derive from the lymphocytes contained in these satellite lymphoid aggregates remains unclear. Conventional and immunohistochemical stains demonstrated that these inclusions represent apoptotic mate-rial. The possibility that tumor cells from flat neoplastic lesions of the colorectal mucosa inflict apoptosis upon non-epithelial (i.e. foreign) cells has been entertained.