RESUMO
The purpose of this paper is to report three unpublished cases of so-called "renal malignant fibrous histiocytoma" which should be more appropriately called "renal fibrohistiocytic sarcoma", and to review and analyze the data concerning 41 cases collected from the literature and our three new cases, making a total of 44 cases. Our third case is very interesting; in addition to the fact that this condition is rare, this particular patient also had concomitant nonmalignant ascites and compression of the descending colon, both conditions being rarely associated with renal cancer. The average age of the patients was 58 years; in 66% of the cases the tumor involved the left kidney; 57% of the patients were males; the average tumor size was 12 cm; nephrectomy was performed in 93% of the cases; the average survival was 16 months. In none of the cases was a preoperative diagnosis correctly made. It is concluded that a triad of symptoms and signs (renal pain, weight loss, and large tumor size) as well as a triad of imaging characteristics (areas of low density on the CT scan, hypoechoic areas on ultrasound, and hypovascularity on angiography) may hold the promise of a preoperative diagnosis. It is suggested that the tumor arises from the system of Gerota's fascia-renal capsule.
