Aim: Identification of characteristic clinical findings for early diagnosis of carcinoma associated with anal fistula. Methods: From the perspective of early diagnosis, we compared the clinical characteristics of 13 cases of carcinoma associated with anal fistula with 5 clinical diagnostic criteria defined by Sumikoshi et al. Results: Pain and induration, absence of primary cancer at other sites, and presence of the fistula opening were observed in all cases, while mucinous secretion was observed in 8 cases and duration of anal fistula for more than 10 years in only 5 cases. Pain not relieved by drainage and marked induration without elasticity are differential points from abscesses.
MRI showed hyperintense heterogeneous multifocal cystic lesions in 86% of cases, and endoanal ultrasonography (EAUS)showed lattice structures with septations of various sizes and isoechoic solid components in 83% of cases, all of which were useful for early diagnosis.
Conclusions:The following four findings were useful for early diagnosis: 1) extensive severe induration, 2) pain not relieved by drainage, 3) mucinous secretion, and 4) characteristic MRI/EAUS findings. If even one of these is present, carcinoma associated with anal fistula should be strongly suspected and aggressive biopsy should be performed.