Clinical history: 56-year-old school-bus driver presents with intermittent, vague left sided peri-umbilical pain. On laparoscopy a mass was found surrounding the superior mesenteric pedicle and involving the base of the right colic artery.
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Discussion and answer
This mass consists of fibrosis, chronic inflammation and focal fat necrosis. The fibrous bands infiltrate and surround the fat, forming lobules. Microscopic areas of plump spindle cells positive for SMA, consistent with myofibroblasts are present. Interspersed within the fibrosis and fat lobules are chronic inflammatory cells, predominantly lymphocytes with fewer plasma cells and eosinophils. Alk protein expression is negative. This combination of fibrosis, lipid-laden macrophages, adiponecrosis, and nonspecific inflammatory infiltration is typical of sclerosing mesenteritis – an uncommon non-neoplastic inflammatory process in the mesenteric fat that rises as a pseudotumor, usually involving the small bowel mesentery, fat and, less commonly, the mesentery of the large bowel. Male to female predominance is about 2-3:1 and the incidence increases above age 50. Ischemia, infections, previous trauma, autoimmune disorders, previous abdominal surgery, coexisting malignancies moslty urogenital or gastrointestinal lymphomas are some of the possible risk factors.
Other names: Retractile mesenteritis, Mesenteric nodular panniculitis, Weber-Christian disease, and Mesenteric lipodystrophy.
Clinical presentations are nonspecific and in common with numerous other diseases. There can be partial or complete resolution of the inflammatory process, a non-progressive course, or an aggressive course, characterized by a progressive fibrosis. Most cases have a favorable outcome; however, colonic forms require surgical treatment more often than other forms.