[Hepatic cystic endometriosis with malignant transformation]

Endometriosis, defined as the presence of endometrial tissue outside the uterine cavity, is most frequently located in the pelvic organs. Hepatic endometriosis is extremely rare, and only 12 cases have previously been reported. A wide variety of symptoms have been described, from asymptomatic masses (incidental findings) to acute abdomen. The diagnostic method of choice is abdominal CT, which should always be used in the differential diagnosis of cystic liver masses. Because of the high percentage of malignant transformation, the first-line treatment is surgical resection with adequate safety margins. We report a case of in situ adenocarcinoma arising in a hepatic endometrioma, which was treated with right hepatectomy.