Solitary fibrous tumor of the kidney: a report of two cases and review of literature

Objective To explore the clinicopathologic characteristics and differential diagnosis of solitary fibrous tumor (SFT) of the kidney. Methods We reviewed two cases of SFT in the kidney and examined the histological and immunohistochemical (using EnVision-plus method) features. Results Both cases of SFT occurred in female, aged 33 and 63 respectively. Dull pain in the flank was the most common presenting symptom.Urine frequency, irritation, pain and hematuria were absent. CT images showed space-occupying in the kidney. The histological characteristics showed a tumor with bunchy or wavy-like arrangements. Neoplastic cells were spindle with focally high celluarity. Plenty of blood vessels were identified in the stroma: partial hemangioma or hemangiopericytoma-like structure with palpable bunchy collagen. Immunohistochemical analysis showed that the tumor cells were diffusely positive for CD34, CD99, BCL-2 and focally positive for SMA while negative for HMB45 and CD10. Conclusions The SFT of the kidney is very rare and has the characteristics of low malignant potential. The main treatment of the SFT is surgery with a good prognosis. Definite diagnosis should be based mostly on pathological examination in assistance with immunohistochemical analysis.