A mucinous histochemical study on malignancy of aberrant crypt foci (ACF) in rat colon

The relationship between malignancy and number of crypts (crypt multiplicit y) comprising aberrant crypt foci (ACF) was investigated, by studying chang es in the mucous nature of ACF with 5 crypts or less, ACF with 6-13 crypts, adenomas and invasive adenocarcinomas induced by 1,2-dimethylhydrazine in distal colon of rats. A paradoxical Con A-staining was performed for goblet cell mucins. Of the sulfomucin-dominant ACF with 1-3 crypts, 82.6% had lab ile class III mucin, similar to the distal colon in the normal rats. Howeve r, in most of the goblet cell mucin produced by the ACF with 4-5 crypts wit h an indicated relation to colorectal carcinoma or the sialomucin (SiM) -do minant ACF with 1-3 crypts, mucin types other than class I were rarely pres ent. The incidence of class I mucin decreased with the increase in crypt mu ltiplicity of ACF or in the degree of histological malignancy, with the low est incidence of 40% in adenocarcinomas. In contrast, the incidence of clas s II mucin increased markedly with the increase in crypt multiplicity of AC F or in the degree of histological malignancy, with the highest incidence i n adenocarcinomas (95%). The ACF with 6-13 crypts had a mucous profile simi lar to that of adenomas. These results suggested that malignancy of ACF rel ated to the crypt multiplicity. In the ACF with 1-3 crypts, SiM-dominant AC F had the potential to progress to malignant lesions.