Clear cell adenocarcinoma arising in endometriosis of a previous episiotomy site.

Background: Malignant transformation of endometriosis in an episiotomy site is rare.

Case: A 42-year-old woman presented with a palpable mass, 2.5 cm in size, just inside the posterior commissure of the vagina, at the site of a previous episiotomy for a vaginal delivery. Three years previously, an endometriotic cyst had been excised at the same site, and the patient had been treated with a gonadotropin-releasing hormone analogue for 6 months. Biopsy revealed a clear cell adenocarcinoma arising in endometriosis. The patient underwent radical surgery alone without adjuvant therapy. At 10-month follow-up, there was no evidence of recurrence.

Conclusion: Patients who experience a recurrence of extragonadal endometriosis after prior therapy should be monitored carefully for malignant degeneration.