Radiation-induced inflammatory malignant fibrous histiocytoma of the ileum.

A case of inflammatory malignant fibrous histiocytoma of the ileum seemingly induced by radiation is described. A 50-year-old female with a past history of uterine cervical carcinoma and postoperative radiation therapy presented with abdominal pain, fever and leukocytosis. The subserosa of the distal part of the ileum showed a diffuse dense, neutrophilic and lymphocytic infiltrate with dispersed atypical, short spindle- or plump oval-shaped histiocyte-like cells. Pleomorphic mono- or multinucleated giant cells with bizarre nuclei were also intermingled in the lesion. Immunohistochemically, the tumorous atypical cells were positive for vimentin, α-smooth muscle actin, α-1 antitrypsin and granulocyte colony-stimulating factor. No EBV genomic sequences were detected by in situ hybridization. Flow cytometry showed an aneuploid DNA content with high S-phase fraction. The patient was well with no evidence of tumor at 5 months after surgery. It is important to include this type of tumor in the differential diagnosis of small intestinal lesions accompanied by fever and leukocytosis following radiation.