A case of inflammatory malignant fibrous histiocytoma of the retroperitoneum

We report the case of a 68-year-old woman with inflammatory malignant fibrous histiocytoma of the retroperitoneum. Macroscopically, the cut tumor surface showed a solid mass with cystic components. Histologically, the tumor consisted of multinucleated giant cells, atypical large cells, many neutrophils, and xanthoma-like foamy cells within collagen fibers. Cytologically, large atypical cells appeared with neutrophils or xanthoma-like foamy cells as a background. Large atypical cells had multinucleated and bizarre nuclei. Some tumor cells resembled Reed-Sternberg cells. Immunohistochemical staining ruled out leiomyosarcoma and gastrointestinal stromal tumor. She has been followed up for 2 years without any evidence of local recurrence.