Primary perineal endometriosis - a case report and literature review.

Endometriosis is a common gynecological disease caused by the implantation of active endometrial cells outside the uterine cavity. In most cases, endometriosis occurs in the pelvic area, such as the ovary, Douglas' pouch, or uterine sacral ligament. Some rare cases of extrapelvic endometriosis can also occur in the perineum, urinary system, gastrointestinal tract, nervous system, chest, subcutaneous tissue, and skin. Endometriosis of the perineum is usually secondary to obstetric trauma, such as perineal laceration or episiotomy. To date, few cases of spontaneous perineal endometriosis have been reported. Herein, we report a rare case of spontaneous deep perineal endometriosis. Notably, the patient had typical symptoms of regular pain during menstruation with no history of delivery or perineal trauma. The patient recovered well after postoperative gonadotropin releasing hormone agonist injection.