Renal solitary fibrous tumour: A rare pathological entity.

A solitary fibrous tumour (SFT) is a rare mesenchymal cell neoplasm that can develop at any site. SFT of the kidney is extremely rare. Recently, we had a case of solitary fibrous tumour involving the left kidney in a 71-year-old female patient. The SFT was incidentally found by imaging modalities at the time of a physical workup. Computed tomography and retrograde pyelography showed a 4 × 3.5 × 4-cm nodular mass in the middle poles of the left kidney adjacent to the renal pelvis. A laparoscopic radical resection of the left kidney was performed. The tumour was well-circumscribed and composed of a mixture of spindle cells; microscopically, we found dense collagenous bands. Immunohistochemical studies showed strong reactions with CD34, bcl-2 and CD99. A nuclear positivity with Ki-67 was observed in less than 1% of cells. The tumour was negative for desmin, SMA and CD117. Histopathological and immunohistochemical studies confirmed the diagnosis of a solitary fibrous tumour.