Aberrant Crypt Foci: Histopathologic Classification and Profiles of Mucin Secretion

ABSTRACT

Aberrant crypt foci (ACF) are grossly unidentifiable lesions of the colon and visible only with low-power microscopic examinations after methylene blue stain. To establish the role of ACF in colorectal carcinogenesis, we evaluated the distribution, frequency, histopathological classification, and patterns of mucin secretion of ACF in the colon. A total of 142 aberrant crypt foci were found in 41 colectomy specimen for adenocarcinoma (36 cases) and benign diseases of colon (5 cases). Ten of 142 ACFs were in the ascending and transverse colon, 39 in the descending and sigmoid colon, and 93 in the rectum. The mean number of ACFs in the rectum (0.13 0.11/cm2) was higher than in the ascending and transverse colons (0.019 0.018/ cm2) and descending and sigmoid colon (0.10 0.14/cm2). ACFs were found only in cancer patients. One hundred and twenty ACFs among 142 ACFs identified by topology, were identified on histological examination. We classified ACFs into simple (48.3%), hyperplastic (42.5%), and dysplastic (9.2%) types. All ACFs were infiltrated by the lymphocytes in the stroma and 18 of these accompanied the lymphoid follicles. ACFs have variable histopathologic features and mucin profiles. Some variants of ACFs are at the early stage of the spectrum between benign and malignant.