Diagnostic implications of MR imaging for mucinous adenocarcinoma arising from fistula in ano.

Mucinous adenocarcinoma associated with chronic fistula in ano is rare, and diagnosis is often difficult. Two cases of mucinous adenocarcinoma arising from fistula in ano occur in a patient with longlasting fistulas, persisting for more than 10 years, are presented. In two cases, T2-weighted MR images revealed symptomatic features; that is, the hyperintense heterogeneous content looked like a gathering of various sizes of granules. This is due to the fact that mucinous adenocarcinomas usually consist of the gathering of many small mucous lakes. This finding has the implications in diagnosing mucinous adenocarcinoma arising from carcinoma in ano.