Peritoneal malignant mesothelioma in a patient with recurrent peritonitis.

A patient is presented who developed a peritoneal malignant mesothelioma in association with severe persistent and recurrent diverticulitis. The case is unusual in that a spectrum of mesothelial proliferation was documented beginning initially as benign foci of mesothelial proliferation and passing through a stage of atypical proliferation before terminating as a malignant process. The possible role of the diverticular disease in the pathogenesis of the tumor is discussed.