A case of endometriosis in the right inguinal region connected to the round ligament of the uterus

Here, we report a case of cutaneous endometriosis. A 39-year-old woman presented with a subcutaneous nodule in the right inguinal region with a 1-month history. The patient had undergone infertility treatment for 9 years before she visited us. Computed tomography (CT) analysis revealed a subcutaneous nodule with an indistinct border, ruling out the possibility of adenomyosis of the uterus or inguinal hernia. We performed surgical excision of the nodule. Histopathologically, the nodule was composed of glandular ducts and surrounding stroma that was directlyconnected to the round ligament of the uterus. After ruling out the possibility of an apocrine gland or ectopic mammary gland on the basis of an immunohistochemistryexamination, endometriosis was diagnosed. Cutaneous endometriosis should be considered in the differential diagnosis of a patient with an inguinal subcutaneous nodule.