Idiopathic retractile (sclerosing) mesenteritis and its differential diagnosis.

We report a case of retractile mesenteritis presenting as an abdominal mass with incomplete small-bowel obstruction. Histological features included fat necrosis, fibrosis, elastosis, dystrophic calcification, and chronic inflammation. Lymphatic obstruction resulted in the accumulation of lipid-laden macrophages in the ileal mucosa. Ultrastructurally, myofibroblasts were the principal cells present. The differential diagnosis of retractile mesenteritis is discussed with particular attention to myofibroblastic disorders such as inflammatory pseudotumors, desmoids, retroperitoneal fibrosis, and other uncommon conditions that appear to be morphologically or clinically distinguishable although the etiology and pathogenesis are obscure.