Imaging findings of solitary fibrous tumor of the prostate: a case report.

The imaging findings of a solitary fibrous tumor of the prostate are presented. A 35-year-old male presented with urinary retention and was found on transrectal ultrasonography to have a hypoechoic tumor of the prostate, measuring 5.5 cm in size. Magnetic resonance imaging on, the tumor showed low signal intensity on T1-weighted images and heterogeneous mixed signal intensity on T2-weighted images. Gadolinium-enhanced dynamic study showed gradual enhancement from the periphery to the center, and the enhancement is sustained. On immunohistochemistry, the spindle cells of the tumor showed positive staining for CD34 and bcl-2. Although the tumor was labeled as a low-grade malignancy on account of a low mitotic index (MIB-1 index) of about 5%, the patient developed local recurrence of the tumor with bladder wall invasion 12 months later.