[Retroperitoneal and mesenteric fibrosis. An uncommon "carcinoid syndrome"].

Retroperitoneal fibrosis is an uncommon disease in which dense fibrous tissue proliferates in the retroperitoneum. It frequently consists in an abdominal mass involving alimentary structures, ureters with obstruction, and vascular elements with stenosis. This pathological event may be associated with a history of ergotamine usage or a wide range of conditions including malignancy, injuries and infections. In the case described here, the cause was a midgut carcinoid tumour, releasing high concentrations of serotonin and other metabolites directly into the peritoneal fluid. Because carcinoid tumours of the bowel can remain silent for many years it is possible that similar cases of retroperitoneal fibrosis may be identified only many years after onset. For that reason, a long history of bowel obstruction must be considered a kind of unusual but no less important carcinoid syndrome.