Polypoid and papillary cystitis mimicking a large transitional carcinoma in a patient without a history of catheterization: computed tomography and magnetic resonance findings.

The computed tomography and magnetic resonance imaging (MRI) findings of an unusual case of polypoid and papillary cystitis are described, in which the large size of the mass (5 cm) and no history of catheterization favored the diagnosis of transitional carcinoma before surgery. The MRI findings reflected the pathologic features of this cystitis, featuring edematous fibrovascular cores, which appeared as a central branching pattern of high signal intensity on T2-weighted imaging and with enhancement.