First Reported Pediatric Bladder Inflammatory Myofibroblastic Tumor (IMT) Evaluated and Staged with VI-RADS: CT and MR Findings.

Abstract

INTRODUCTION Inflammatory Myofibroblastic Tumor (IMT) is a rare intermediate softtissue neoplasm that can arise in virtually any organ, including the urinary bladder. Accurate diagnosis is challenging but crucial, as conservative treatment approaches may be feasible. CASE PRESENTATION An 11-year-old boy presented with dysuria and microscopic hematuria. Ultrasound and Computed Tomography (CT) revealed a bladder mass associated with right-sided ureterohydronephrosis. Multiparametric Magnetic Resonance Imaging (mpMRI), performed for local staging using the Vesical Imaging Reporting and Data System (VI-RADS), demonstrated moderate diffusion restriction of the lesion on Diffusion-Weighted Imaging (DWI). However, the extent of bladder wall invasion was not clearly defined. Dynamic Contrast-Enhanced (DCE) T1-weighted SPIR sequences showed disruption of the hypointense muscularis propria with early extension into the ureteral wall at the intramural segment. Histopathological examination of biopsy specimens confirmed an inflammatory myofibroblastic tumor with muscular layer involvement. The patient received five months of chemotherapy with methotrexate and vinblastine, followed by partial cystectomy and ureteral reimplantation. Three years after treatment, follow-up MRI demonstrated no evidence of locoregional recurrence, indicating a complete response. CONCLUSION In this rare case of pediatric bladder IMT, MRI proved valuable for assessing locoregional tumor extent, guiding surgical planning, and evaluating treatment response. In particular, the case highlights the potential role of VI-RADS-based assessment in the staging and management of bladder IMT.