A case of protein-losing enteropathy caused by sclerosing mesenteritis diagnosed with capsule endoscopy and double-balloon endoscopy.

A 75-year-old man presented with abdominal distension, hypoproteinemia, ascites and a 35-mm mass in the small bowel mesentery. Laparotomy was performed, and he was diagnosed with sclerosing mesenteritis. His clinical condition improved, with computed tomography (CT) showing tumor shrinkage and decreasing ascites after administration of prednisolone; however, on drug withdrawal, abdominal fullness recurred and CT revealed an enlarging tumor and increasing ascites. Capsule endoscopy (CE) and double-balloon enteroscopy (DBE) were performed to further investigate hypoalbuminemia, which revealed white villi, white nodules, white debris, and mucosal edema in the jejunum. Biopsies from the jejunal mucosa demonstrated infiltration by chronic inflammatory cells consisting mostly of lymphocytes and plasma cells, with marked lymphangiectasia of the lamina propria and submucosa. A fecal alpha-1-antitrypsin clearance test revealed abnormal leakage from the gastrointestinal tract, confirming that hypoalbuminemia was secondary to protein-losing enteropathy (PLE). The incidence of sclerosing mesenteritis accompanied by PLE is very rare. Only six cases have been reported so far. CE and DBE were helpful for diagnosing this condition, and should be performed in patients in whom the cause of hypoalbuminemia is unknown, and in those with PLE.