[Vestigial retrorectal cystic formations in adults. Apropos of 3 cases].

Primary retro-rectal cystic lesions of the adult are malignant or benign congenital lesions, with a female predominance. In this report, we present 3 cases and try to specify the embryologic origin of these lesions and propose an anatomopathological classification. The various diagnostic methods are studied. Because of infection and risk of malignancy, early complete excision is recommended. We suggest the use of a perineal retro-anorectal approach for low situated, small cysts.