Use of anal endosonography in diagnosis of endometriosis of the external anal sphincter - Report of a case

PURPOSE: Perianal endometriosis is an infrequent form of extragenital endometriosis and is usually situated in episiotomy scars. METHODS: We report a rare case involving the external anal sphincter in a 24 year-old female. The precise anatomical location of the endometriotic lesion was confirmed using preoperative and intraoperative anal endosonography. CONCLUSION: We believe this procedure to be essential when history, digital examination, and proctoscopy are not conclusive in the differential diagnosis of perianal pain or mass. Although hormonal suppression of ten is the therapy of choice in extrapelvic endometriosis, we think surgical excision, respecting the anatomical fiber architecture of the anal sphincter, is the best treatment for perianal endometriosis. Surgical excision is required for histological diagnosis, which is imperative in view of the albeit rare development of malignancy in extragenital endometriosis.