[Malignant solitary fibrous tumour of the kidney: report of a case and cumulative analysis of the literature].

We report the case of a primary metastatic renal solitary fibrous tumour (SFT) and present a cumulative analysis of the literature. A 68-year-old woman presenting with a history of flank pain was diagnosed with a 7 cm renal mass. Further staging showed liver, lung and bone metastases. The patient underwent radical nephrectomy. Microscopically, the tumour consisted of pleomorphic, high-grade spindle cells with high mitotic activity, tumour necrosis and dense collagenous bands. Immunohistochemistry showed the strong expression of CD34 and vimentin, a weak expression of bcl-2 and CD99, and no expression of smooth muscle actin, desmin, S-100, pan-cytokeratin, and epithelial membrane antigen. These findings are consistent with an SFT. For the cumulative analysis, a total of 46 renal SFTs from 35 reports were analysed. Median age at the time of surgery was 52 years and 63% of the patients were female. Sixty-two percent of the tumours were symptomatic, most commonly with flank / back pain (24%). Median tumor size was 6.4 cm. Histologically, 91% of the SFTs were benign and 9% were malignant. One patient died of the disease, while 90% are alive without evidence of disease.