Sarcomatous dedifferentiated renal cell carcinoma mimicking a severe purulent kidney infection

Sarcomatous renal cell carcinomas (SRCCs) originate from a dedifferentiation of renal cell carcinoma (RCC). They are characterized by an aggressive course and very poor prognosis. Less known is their ability to imitate inflammatory diseases of the kidney. The aim of the study was to outline the less usual symptoms of SRCCs in a retrospective analysis of 180 patients operated for RCC in 1997-2001. In 11 (6.1%) patients (8 men and 3 women, age 40-76 years, mean age 60 years) SRCC was present. The pTNM classification, results of histological examination, the stage of RCC dedifferentiation and survival after the operation are presented. In almost every patient SRCC was diagnosed at a late stage with combined histological variants of RCC. Survival of the patients after the operation ranged from 1 to 19 (average 8.8) months. In 2 patients an atypical clinical picture imitated abscess of the kidney and calculous pyonephrosis. The authors warn that in spite of the clinical signs of inflammatory disease of the kidneys, a tumorous origin should be excluded. In doubtful cases a quick peroperative biopsy and histology should be performed. Sometimes only a definitive histological examination can reveal the tumorous origin of the disease.