# High grade endometrioid carcinoma arising from deep infiltrating endometriosis extending deeply into the pelvis: a case report

## TL;DR

A rare case of high-grade endometrioid carcinoma from deep infiltrating endometriosis was effectively treated with concurrent chemoradiation therapy after incomplete surgery.

## Contribution

This case report highlights the effectiveness of concurrent chemoradiation therapy in treating localized high-grade endometrioid carcinoma arising from deep infiltrating endometriosis.

## Key findings

- Concurrent chemoradiation therapy achieved a complete response in a patient with localized high-grade endometrioid carcinoma.
- The patient had incomplete surgical resection but showed significant improvement with adjuvant CCRT.
- Treatment of malignant transformation of extra-gonadal endometriosis should consider lesion localization and organ involvement.

## Abstract

Carcinoma arising from deep infiltrating endometriosis (DIE) and extending into the rectovaginal septum is extremely rare. Its treatment requires extensive surgical resection and adjuvant chemotherapy. Herein, we present a case demonstrating that concurrent chemoradiation therapy (CCRT) can achieve effective cancer control. A 44-year-old nulliparous woman had been taking oral contraceptives due to pelvic endometriosis for years. The tumor markers have increased, and the tumor was localized within the pelvic cavity, particularly around the vesicouterine pouch and the rectouterine pouch. The patient underwent extensive surgery, but resection was incomplete. Considerable amounts of cancer tissue were retained in the left pelvic wall. CCRT was chosen as an adjuvant therapy due to localized high-grade adenocarcinoma, resulting in a complete response. Treatments for the malignant transformation of extra-gonadal endometriosis vary depending on the involved organs and the degree of extension. CCRT could be selected if the lesion is localized.