Background: Adenosarcoma arising in inguinal endometriosis is a rare clinical entity.
Case: A 47-year-old nulligravida presented with a persistent and enlarged right groin mass. Sixteen years earlier she had undergone total abdominal hysterectomy and bilateral salpingo-oophorectomy for endometriosis and was placed on estrogen therapy. Surgical en bloc excision of the 12 x 4 cm inguinal mass revealed adenosarcoma arising in endometriosis.
Conclusion: Although a rare entity, adenosarcoma arising in inguinal endometriosis should be included in the differential diagnosis for those patients with a history of endometriosis and chronic unopposed estrogen therapy who present with a groin mass.