A Case of IgG4-related Sclerosing Mesenteritis.

A 60-year-old African-American male presented to the emergency department with abdominal pain and distention associated with decreased appetite and weight loss for several weeks. A computed tomography (CT) scan of the abdomen and pelvis showed an 8 cm mesenteric mass with surrounding stranding and poorly defined borders. The patient underwent exploratory laparotomy and complete resection of the mass since the frozen section could not give a definite diagnosis. Histopathology showed fibro-adipose tissue with lymphoid hyperplasia, vague nodular collections of foamy histiocytes with giant cell reaction, marked chronic inflammation, fat necrosis, and prominent sclerosis/fibrosis. Methenamine silver and acid-fast stains were negative for fungal and mycobacterial organisms respectively. Examination of tissue with immunohistostains showed increased immunoglobulin G4 (IgG4)-positive plasma cells. Other features observed were scattered areas of phlebitis, pockets of tissue eosinophilia, and focal storiform fibrosis leading to the diagnosis of IgG4-related sclerosing mesenteritis. The patient did not require steroids after the surgical resection and was disease free at six-month follow up.