CT and MRI Findings of Inflammatory Myofibroblastic Tumor in the Bladder

Inflammatory myofibroblastic tumor (IMT) of the urinary bladder is a rare soft tissue tumor characterized by spindle cell proliferation with inflammatory cell infiltration. We present a case of bladder IMT occurring in a 6-year-old boy. Pretreatment CT images depicted a polypoid and broad-based mass measuring 18 mm in the superior to the front wall of the bladder, and the mass showed isodensity on precontrast image and ring enhancement of the mass after the intravenous administration of contrast material. Pelvic MRI demonstrated the 18 × 17 × 16 mm broad-based mass, suggesting submucosal tumor in the dome of the bladder. The mass showed low-to-moderate signal intensity on T1-weighted images and slight high signal intensity on T2-weighted images and restricted diffusion with low signal intensity on ADC map and abnormal high signal intensity on DWI. Transurethral resection of the bladder tumor and partial cystectomy were undertaken, and the pathology revealed IMT of the bladder. We suggest its inclusion in the differential diagnosis of cases of a polypoid and broad-based mass on the superior wall or the front wall of the bladder with ring enhancement on contrast-enhanced CT and MRI.