[Solitary Fibrous Tumor of the Kidney]

A 59-year-old woman was referred to our hospital with the finding of an incidentaloma in her right kidney. Computed tomographyand magnetic resonance imaging showed a solid tumor, approximately8 cm in diameter, at the lower pole of the right kidney. Partial nephrectomy was performed without a renal vessel clamp. Histopathologically, fibroblast-like spindle cells were proliferating with rich collagenous fibers, and tumor cells were infiltrated into the renal parenchyma. The tumor cells were stained positive with CD34, CD99, and bcl-2. The tumor was diagnosed as solitaryfibrous tumor originating from the kidney based on these histopathological findings. The patient was followed 3 years after surgery with neither recurrence nor metastasis.