Cutaneous Endometriosis: A Differential Diagnosis of Umbilical Nodule

Endometriosis is a chronic disorder characterized by the presence of ectopic functional endometrial tissue outside the uterine cavity and which affects about 10% of all women of reproductive age. Cutaneous endometriosis, usually localized in the abdominal wall, is a rare entity. We report the case of a nulliparous woman with an acute painful umbilical nodule that slowly increased in size during the days prior to observation. The lesion was surrounded by a painful periumbilical subcutaneous plaque. The patient denied associated constitutional symptoms and reported two similar episodes in the previous two years. A skin biopsy was performed, and histopathologic examination was consistent with the diagnosis of endometriosis. This article reviews this disease particularly rare in nulliparous and highlights the importance of recognizing this clinical presentation of endometriosis due to its frequent association with pelvic disease that can lead to reduced fertility.