service de gastroentérologie et endoscopie digestive,
Mesenteric panniculitis (MP) is a non-specific inflammatory process affecting the adipose tissue of the mesentery. Symptoms may be absent and the process incidentally found on CT scan or there may be fever, abdominal pain, vomiting or diarrhea at presentation. MP is characterized on CT scan by an increased mesenteric fat density which gives the aspect of “misty mesentery” and the presence of lymph nodes within the fatty mass ; sometimes the presence of an hypodense halo surrounding blood vessels and nodes is at the origin of the “fat ring sign”; hyperdense pseudocapsule surrounding the mesenteric fat may also be observed. Mesenteric non-Hodgkin lymphoma is the major differential diagnosis to rule out; it may be differentiated from MP by the size and the shape of mesenteric nodes on CT. In the literature, MP is variably associated with neoplastic processes, and/or with benign abdominal and retroperitoneal disorders. The cancer is usually distant from the peritoneum and diagnosed before or concomitantly to MP; it should be searched for by the usual clinical, imaging and biology examinations. Sclerosing forms of MP are rare; they represent a distinct histologic entity with predominant fibrotic tissue and are mostly disclosed at surgery. Treatment is not standardized and is mandatory only in symptomatic cases. It relies upon corticosteroids, sometimes associated with other anti-inflammatory or immunosuppressant drugs, and occasionally on surgery, in sclerosing mesenteritis associated with complications.