[Endometriosis of the transverse colon--a rare localization]

A 65-year-old woman with no complaints came to our hospital for a colonoscopy because of a family history of a colorectal carcinoma. Because of postmenopausal complaints she had been undergoing estrogen therapy for the past five years.

Colonoscopy revealed a 2 x 2 cm polyp like structure with central tissue proliferation in the transverse colon. Neither chromoendoscopy with indigocarmine nor multiple biopsies indicated an adenomatous glandular proliferation. Miniendosonography revealed the image of a tumour located in the muscularis propria. DIAGNOSIS AND CLINICAL COURSE: As a malign process could not definitely be excluded, a colon segment resection was carried out by laparoscopy. In the operative specimen there was a 2 x 2 cm large tumour growing under the mucosa. Histologically it was an intramural manifestation of an extragenital endometriosis in the area of the muscularis propria with resulting nodular proliferation of the local muscle system. The ectopic endometrial glands in the area of the endometriosis revealed a complex hyperplasia without atypical features, an image suggesting oestrogen stimulation.

In many cases the diagnosis of an intestinal endometriosis can not be made through a non-invasive diagnostic method such as colonoscopy with biopsy because of the intramural localisation in the muscularis propria. In order to safely rule out a malignant lesion, in unclear cases a resection should be aimed at.