Case presentation: A middle-aged woman presented to the emergency department with a chiefcomplaint of abdominal pain, fever, vomiting, and diarrhea. Abdominal computed tomographyrevealed gastric pneumatosis and air in the portal system. The patient had an unfavorable clinicalcourse with pneumoperitoneum and septic shock due to secondary peritonitis. She underwentemergency laparotomy where neoformation of the mesentery root was found with infiltration of thesmall intestine and jejunal perforation. The anatomopathological study of the tumor revealed that itwas a desmoid tumor.

Discussion: To our knowledge this is the first report in the literature of gastric pneumatosis as theinitial presentation of a mesenteric desmoid tumor. Although it usually has a benign clinical course,its locally invasive characteristics can lead to critical illness. Physicians shouldn’t overlook thesetypes of complications, as early identification and surgical intervention can modify the prognosis andshorten hospital stay.