Clear cell carcinoma of the pelvic side wall arising from endometriosis

Endometriosis is a condition wherein an ectopic layer of endometrial tissue arises in an extra-uterine location, often effecting significant pelvic pain and infertility. While very uncommon, there have been reported cases of endometriosis undergoing malignant transformation, frequently involving the ovaries and seldom in extra-gonadal regions. We recount a case depicting a 63 year-old woman who presented with an apparent inguinal hernia in 2017; she was ultimately diagnosed with a pelvic side wall clear cell carcinoma and attendant metastatic disease to the medial groin, which emanated from endometriosis. Malignant transformation of endometriosis identified in the pelvic side wall is a very rare finding. Nevertheless, oncologists should maintain a high index of suspicion in patients with a history of endometriosis or pelvic surgery. •Malignant endometriosis periodically invades the ovaries and extragonadal regions.•We describe a pelvic side wall, clear cell carcinoma arising from endometriosis.•The disease may develop in patients with a history of endometriosis or pelvic surgery.