ABSTRACT: Endometriosis is a benign condition of the female genital system, characterized by endometrial tissue external to the uterine cavity. Of all cases with endometriosis, the incidence of umbilical endometriosis is only 0.29%. Umbilical endometriosis typical presents with symptoms including cyclical pain, bleeding, and swelling of the nodule. Morphological changes in the epidermis, as in this case, simulating a seborrheic keratosis both clinically and microscopically, can initially mask the underlying endometriosis and prolong the course of treatment. A thorough anamnesis and examination revealing the characteristic symptoms and findings coupled with a representative biopsy is essential to correctly diagnose umbilical endometriosis.