Solitary fibrous tumor of the kidney: Magnetic resonance imaging characteristics in 4 patients.

To investigate the characteristics of magnetic resonance image (MRI) in solitary fibrous tumor (SFT) of the kidney.MRI findings and clinical features of SFT of the kidney in 4 patients (2 men and 2 women with a mean age of 37.8 ± 8.7 years) were reviewed retrospectively. All patients were scanned by a 3.0-T magnetic resonance (MR) imaging system and the lesions were detected with emphasis on size, shape, location, margin, presence of pseudocapsule, signal intensity, degree of MR enhancement, and apparent diffusion coefficient (ADC).The 5 tumors from 4 patients were located in renal parenchyma (n = 1), renal pelvis (n = 3), and renal capsule (n = 1). On MRIs, the tumors were round (n = 1) or oval-shaped (n = 4), and presented pseudocapsule (n = 2) and well-circumscribed margins (n = 3) can be found. On T2-weighted images (T2WIs), solid components of the tumor presented homogeneously mild hypointensity or isointensity (n = 4) compared with the renal cortex. On diffusion-weighted images (DWIs), the lesions showed normal or mild hyperintensity (n = 4) with mean ADC of 1.687 × 10 mm/s. On dynamic contrast-enhanced MRIs, all lesions showed progressively mild enhancement. In the follow-up of 24 to 36 months after the surgery, 3 patients survived and 1 deceased.The SFT of the kidney appeared as a circle or oval and presented homogeneously mild hypointensity or isointensity on T2WIs, hyperintensity on DWIs, and progressively mild enhancement on DCE MRIs.