Perineal endometriosis on an episiotomy scar: diagnosis based on clinical, radiological, and hormonal criteria

Endometriosis is a chronic, non-cancerous gynecological disorder that is typically observed in women of fertile age. It describes the presence of functional endometrial components, glands and stroma outside the endometrial cavity, most often involving pelvic structures such as the ovaries, peritoneum, and uterine ligaments. Perineal endometriosis is a rare form of extrapelvic endometriosis, with an estimated incidence of between 0.3% and 1%. We report the case of a 36-year-old woman, gravida 1 para 1(G1P1), with a history of vaginal delivery and no known history of endometriosis, who presented with a painful mass located on the right perineal scar two years after undergoing a mediolateral episiotomy. The mass was associated with cyclical pain and significantly impaired quality of life. Clinical examination, combined with ultrasound and Magnetic Resonance Imaging (MRI), suggested the diagnosis of perineal endometriosis in the absence of other endometriotic lesions. As the patient declined surgery, hormonal therapy was initiated, resulting in marked symptom improvement at 8-month follow-up. Although histological confirmation was not obtained, the typical clinical presentation, evocative MRI features, and favorable response to hormonal therapy supported the diagnosis of perineal endometriosis. This under-recognized entity should be systematically considered in women of reproductive age presenting with cyclical perineal pain following episiotomy.