ABSTRACT
Perineal fistulae can be divided pathologically into congenital fistulae lined by epithelium and acquired ones whose occurrence is closely related to the abscess-fistula sequence and accordingly are usually lined by granulation Acquired fistulae may be further divided according to their mode of into delayed onset fistulae relative to the initialing event and the classical perianal fistulae and its differential diagnoses. Missing the latter lesions for the well acknowledged perianal fistula may have dire consequences on results of therapy in the form of repeated recurrences or the dreaded grades of incontinence. Most of these lesions require the appropriate chemotherapeutic. agents with rather less aggressive surgical maneuvers if compared to the corresponding techniques in classical perianal fistulae. The last two considerations make preoperative identification of these ions of paramount importance