[Retroperitoneal benign fibrous histiocytoma.  Presentation of a case]. 
Presentation of one case of an extraperitoneally located Benign Fibrous Histiocytoma in a 59-year old male.  Retroperitoneal tumours are extremely rare neoplasias, malignant in about 85% cases 35% of which are sarcomas.  The benign fibrous histiocytoma is most often located in subcutaneous tissues, a deeper location being exceptional.  They are usually clinically silent entities until size causes a shift or compression of other organs which cause the clinical signs and symptoms.  In many cases, the neoplasia is detected by ultrasound.  Computerized Axial Tomography is the technique that provides more data for the establishment of diagnosis, although for many authors Nuclear Magnetic Resonance can be more defining.  The primary therapy is surgical removal, but relapses can occur if full exeresis is not achieved.