Endometriosis in the rectus abdominis muscle: case report and literature review.

Endometriosis is characterized by the presence of histologically normal endometrial tissue outside the uterine cavity. Endometriosis occurs most commonly within the pelvis. Extrapelvic endometriosis is less common, but can involve nearly every organ in the body. We present a patient in whom endometriosis was discovered in the rectus abdominis muscle and discuss the imaging findings and histopathology.