A case of malignant solitary fibrous tumor of the prostatic urethra.

A 68-year-old male with dementia presented with gross hematuria. On plain CT, a mass was found at the base of the prostate with intravesical protrusion. On MRI, the mass was well-circumscribed and showed slight hyperintensity compared to the skeletal muscle on T 1 weighted imaging and high intensity on T 2 weighted imaging. On dynamic study, the tumor showed mild enhancement in the early phase and increased enhancement in the delayed phase, and the mass appeared continuous with the prostatic urethra. On follow-up MRI at approximately 10 months, the mass had increased in size. Pathologically, the tumor was located in the muscularis of the prostatic urethra and consisted of spindle cells with fascicular and storiform patterns of growth, and exhibited strong diffuse expression of CD34. The tumor was hypercellular, and a significant number of mitoses were observed. Therefore, this tumor was diagnosed as malignant solitary fibrous tumor (SFT) of the prostatic urethra.