Retroperitoneal endometriosis causing unilateral hip pain

Background: The usual symptoms of endometriosis are secondary dysmenorrhea, dyspareunia, and infertility, but when located in the retroperitoneal space, it might have atypical symptoms that delay diagnosis and postpone therapy. Case: A young nulligravida presented with secondary dysmenorrhea and concurrent cyclic hip pain. Recent laparoscopy was reportedly normal. Computed tomography (CT)-directed percutaneous needle biopsy of a retroperitoneal mass showed endometriosis. Laparotomy with retroperitoneal dissection removed the endometriosis, and operative arthroscopy released strictured hip tendons improving her hip pain and limp. Conclusion: Retroperitoneal endometriosis presenting as hip pain was diagnosed by CT-guided percutaneous needle biopsy permitting removal by a multidisciplinary surgical approach.