Calcifying fibrous pseudotumor of mesentery presenting with acute peritonitis: Case report with immunohistochemical study and review of literature

Calcifying fibrous pseudotumor (CFP) is a benign soft tissue lesion composed of thick collagen bundles, scattered fibroblasts, and psammomatous and dystrophic calcifications, located most commonly in the extremities and trunk of children and young adults. The present case in a 36-year-old woman is to the best of our knowledge the first report of a large CFP confined to the mesentery, which, because of torsion, led to acute peritonitis and emergency laparotomy. The typical histologic features were accompanied by a prominent myofibroblastic proliferation along with inflammatory response at the periphery of the lesion. The spindle cells of the lesion were positive for vimentin and focally for CD34 and smooth-muscle actin. Review of the literature and discussion of differential diagnosis in this report focuses on abdominal CFP and other intraabdominal soft tissue lesions, some of which may be precursors of CFP.