A case of inguinal endometriosis with difficulty in preoperative diagnosis.

An unusual case of endometriosis involving the right round ligament in a 40-year-old woman is presented. After giving birth to two children, she first noticed a tender mass in the right groin at the age of 36. It didn't change in size but pain appeared at the age of 38, disturbing her daily life. A poorly circumscribed elastic hard mass, measuring 3 cm in diameter, was palpable in her right inguinal region. Magnetic resonance imaging demonstrated a 2x3 cm mass in the right inguinal canal. At operation, a mass was found to be in continuity with the round ligament at the inguinal canal. Histological diagnosis was endometriosis. After operation, she was completely relieved of pain. It is important to include endometriosis in the differential diagnosis for painful inguinal masses in women of childbearing age.