We report the case of a young woman with recurrent unilateral hip pain. A polylobular cystic mass was found in the right adductor space. Magnetic resonance imaging (MRI) revealed a polynodular mass migrating from the intrapelvic region along the obturator nerve. Because of a history of cyclic pain and the characteristics on MRI (hypointense rim and spots of spontaneous hyperintense signal on T1-weighted images), an endometrioma was suspected. The diagnosis of endometriosis was later confirmed through ultrasound-guided biopsy.