摘要Meckel's diverticulum is the most common congenital anomaly of the gastrointestinal tract,affecting approximately 2％ of the population.It is a true diverticulum occurring on the anti-mesenteric border of the distalileum,typically within 100 cm of the ileo-caecal valve.Neoplasms arising in Meckel's diverticula are uncommon,and those reported in the literature are mainly carcinoid tumors,followed by gastrointestinal stromal tumors (GIST) and benign leiomyomas.Adenocarcinomas are extremely rare.Tumors in Meckel's present non-specifically with gastrointestinal complaints,such as bleeding,obstruction,inflammation or perforation.The suspicion of a Meckel's tumor is often not thought of at the initial.In this article we describe a 57-year-old woman who presented with massive rectal bleeding and severe anemia,later found to be caused by a adenocarcinoma arising from Meckel's diverticulum.The tumor was unfortunately highly aggressive.Multiple liver metastases had already existed when we discovered the primary mass.Later we performed a partial resection of the ileumto cease the bleeding.Meckel's diverticulum and the tumor were resected simultaneously.The pathological diagnosis confirmed adenocarcinoma arising from the Meckel's diverticulum.The final stage was pT4NxM1,stage Ⅳ according to the Union for International Cancer Control (UICC) classification.After operation we gave the patient firstline,mFOLFOX6 chemotherapy,but it turned out to be not effective.Rapid progress of the liver metastases and suspicion of multiple lung metastasis in short time after therapy indicated a bad outcome.We believe this is the first case of adenocarcinoma in a Meckel's diverticulum to be reported in domestic literature.The diagnosis of Meckel's tumor should be considered as inpatients' acute gastrointestinal complaints;when found incidentally at laparotomy,it should be carefully examined for any gross abnormality and resection should be considered.