Providing new insights into the endometriosisassociated cancer arising in episiotomy scars.

Endometriosis-associated malignancy in an episiotomy scar is rare. The predictive factors are poorly understood as are the mechanisms and pathways associated with implantation and malignant transformation. In this study we describe the cases reported in the literature of malignancies arising in endometriosis foci of an episiotomy scar. We identified 5 cases described between 1990 and 2016. These cases represent recurrence of endometriotic lesions in an episiotomy scar after previous diagnosis of endometriosis, 3 to 25 months before. Histology revealed clear cell tumours in 4 cases and a serous papillary carcinoma. The approach encompassed surgical removal for diagnosis and as part of the therapeutic strategy. Adjuvant treatment was performed depending on classical prognostic factors. Mechanisms of endometriosis implantation in scars include the influence of estrogens in the healing process and activation of COX-2, aromatase and matrix metalloproteinases. Nevertheless, for malignant transformation, other pathways seem to play a role, namely inflammation, immune response and oxidative stress, induced by iron deposits due to haemorrhage. Further studies are needed to allow the establishment of a predictive model for malignant transformation of endometriosis in episiotomy scars.