Retroperitoneal fibrohistiocytic tumors in children: report of five cases.

Five rare retroperitoneal fibrohistiocytic tumors of children are described mainly in reference to the pathological aspects. A more detailed description is given of a retroperitoneal xanthogranuloma, including an ultrastructural study. This case is particularly interesting for its rapid transformation into a fibroxanthosarcoma. The other cases include two fibroxanthosarcomas, a storiform fibrous xanthoma, and a malignant histiocytoma. The most difficult points in the recognition and in the differential diagnosis of these tumors are discussed, and emphasis is placed on some interesting pathological features. Prognosis of such tumors appears difficult to assess from our series since two patients died in the immediate postoperative period, one died one and a half years after the discovery of the tumor, and two are alive and well, but with a short follow-up.