Cutaneous umbilical endometriosis.

A 35-year-old woman presented with a four-month history of a tender umbilical nodule that bleeds during her menstrual period. Physical examination showed a hyperpigmented umbilical nodule. A biopsy specimen showed fibrotic dermis with increased numbers of blood vessels and scattered glandular structures with areas of hemosiderin deposition consistent with a diagnosis of endometriosis. Cutaneous umbilical endometriosis is rare, with an estimated incidence of 0.5 to 1.0 percent. Although anti-gonadotropin medications, such as danazol, have been used for symptomatic control, but surgical excision is the treatment of choice owing to the possibility of malignant degeneration of cutaneous endometriosis.