Inflammatory myofibroblastic tumor of the bladder: Computed tomographic features.

Inflammatory myofibroblastic tumor (IMT) is a rare tumor with intermediate biologic potential, in which lack of understanding often poses difficulties in preoperative diagnosis and treatment. The aim of the present study was to characterize the computed tomography (CT) features of the bladder IMT. The CT images of nine pathologically confirmed bladder IMT were retrospectively reviewed. All patients underwent both unenhanced CT and contrast-enhanced CT. The diameter, location, contour, growth pattern, margin, boundary, density and enhancement pattern of the lesions were assessed. The mean Ki67 value of an irregular blood clot was 18% and that of no blood clot was 12%. A total of eight (89%) patients had one tumor and 1 (11%) patient had multiple tumors. An endophytic growth pattern was observed in 4 (44%) patients, an exophytic growth pattern in 2 (22%) patients, and a mixed growth pattern in 3 (33%) patients. The tumor manifests morphologically as either polypoid (n=5), or cauliflower-like (n=1) soft-tissue mass with a wide base in the cavity, or a limited thick-walled (n=3). The tumor margins were smooth (n=8) or lobulated (n=1), and the tumor boundaries were either clear (n=7) or ill-defined (n=2). The lesions showed either ring-shaped (n=3) or heterogeneous (n=6). The polypoid and cauliflower-like soft-tissue mass showed a symmetrical change in the center of the lesion after enhancement. The bladder IMT is mostly a single polypoid nodule in the superior wall, mostly endophytic growth, with ring-haped enhancement and symmetrical change after enhancement as its characteristic manifestations.