Retrorectal cyst-hamartomas. Report of two cases with adenocarcinoma developing in one.

The clinical and pathological features of two cases of retrorectal cyst-hamartoma are presented. Both lesions were characterized by the presence of cysts lined by mucus-producing, ciliated and transitional epithelium. The anatomical and histological findings in our cases of retrorectal cyst-hamartoma are in favor of an embryologic origin from remnants of the postanal gut. The differential diagnosis includes teratomas, dermoid cysts, duplication cysts of the rectum, anal gland cysts, and anal gland carcinomas. To avoid complications, particularly malignant transformation, early complete excision is recommended.