[A very rare submucosal tumour of the rectum - primary endometrioid adenocarcinoma of the rectum wall]

A 56-year-old female, with a past history of hysterectomy 13 years previously due to uterine myomata, presented with complaints of pain around the anus of a few months duration. Three years previously she underwent a colonoscopy, which was found to be unremarkable. A high suspicion of a submucosal tumour of the rectum in endoscopic examinations was confirmed by endoscopic ultrasound. The biopsy could not specify the tumour characteristics. Based on the diagnosis of a 4 cm submucosal tumour with infiltration of bowel wall and regional lymph nodes the affected segment was resected. Histolopathology revealed an adenocarcinoma involving tissue from the outer bowel wall to the submucosa. However, immunohistochemistry revealed an endometrioid adenocarcinoma, suspicious for primary endometrioid adenocarcinoma of the ovary with rectum metastasis in the absence of a uterus. But this assumption could not be confirmed in the excised ovary. The tumour cells were immunopositive for cytokeratin 7, CA 12 - 5, vimentin and oestrogen receptor, but negative for cytokeratin 20 and CDX-2. Ultimately, we report a very rare case of primary endometrioid adenocarcinoma arising in endometriosis in the rectum wall and presenting as a submucosal tumour.