[Malignant fibrous histiocytoma of the retroperitoneum. Clinico-diagnostic considerations apropos of a clinical case].

The malignant fibrous histiocytoma is a tumor whose histological origin is still unclear. It occurs in the deep soft tissues and is only rarely found in the retroperitoneum. Because of scarse symptomatology during growth, the tumor is usually only diagnosed when it has reached considerable dimensions. Retroperitoneal origin is therefore difficult to diagnose by either ultrasonography or CT. Needle biopsy is at present the sole method which allows a precise diagnosis of the lesion to be made.