A 40-year-old woman was referred to our department because of constipation and hematochezia about 3 days before menstruation. Colonoscopy revealed a slightly elevated lesion in the sigmoid colon. Histopathological examination revealed non-specific colitis. Three months later, a second colonoscopy during menstruation revealed an elevated lesion with an irregular surface and erythematous mucosa. Histopathological examination revealed ectopic glands in the muscle layer.
Estrogen and progesterone-receptors, and CD10 stained positively on immunostaining. Therefore, we made a diagnosis of endometriosis of the sigmoid colon. Gonadotropin-releasing hormone agonist treatment was performed once a month for 6 months. Endoscopy revealed reduction of the elevated lesion with irregular surface and erythematous mucosa. Histopathological examination showed no evidence of endometriosis. The patient is still being followed-up regularly.
