Sclerosing mesenteritis is one of many terms that describes a spectrum of inflammatory disorders that affect the mesentery. The mesentery is the membrane that anchors the small intestine to the back of the abdominal wall. The condition mostly affects men between their 40s and 60s, but women and children can also be affected. It may result in a variety of symptoms including abdominal pain, nausea and vomiting, constipation or diarrhea, weight loss, and fever. Some people have an abdominal mass. The cause of the condition is poorly understood. Suggested possible causes have included previous abdominal surgery or trauma, autoimmunity, paraneoplastic syndromes, ischemic injury, and infection.