Clinicopathological analysis and outcomes of inflammatory myofibroblastic tumours of the urinary bladder

Objectives To describe clinical, imaging, and histopathological characteristics of inflammatory myofibroblastic tumour (IMT) of the urinary bladder and provide initial management and surveillance recommendations. Patients and Methods We identified patients with IMT of the bladder treated at our facility from 1998 to 2020. Categorical variables were analysed with chi‐square and Fisher’s exact tests and continuous variables with the Mann–Whitney U‐test. Kaplan–Meier analysis was performed for recurrence‐free survival. Results IMT was diagnosed in 35 patients with median (interquartile range [IQR]) follow‐up of 20 (11.5–68.5) months. At initial diagnosis 86% were clinically organ‐confined, 9% locally advanced, and 5% metastatic. Majority of patients (92%) had residual disease on re‐staging transurethral resection (TUR). Of the 15 patients with organ‐confined disease managed initially with TUR alone, five (33%) recurred at a median (IQR) of 5 (3.0–5.5) months from initial diagnosis. Presentation with visible haematuria was associated with recurrence (100% in recurrence vs 40% in non‐recurrence groups, P = 0.044). There were no patients who developed a recurrence beyond 6 months after diagnosis. Partial or radical cystectomy was required in 23% and 9% of patients, respectively. One patient presented with metastatic disease associated with anaplastic lymphoma kinase (ALK) translocation and achieved a durable complete remission with 7 months of crizotinib therapy. Conclusions No patient with IMT treated with aggressive endoscopic management developed recurrences beyond 6 months. There were additionally no recurrences noted after definitive radical or partial cystectomy. These data support organ sparing therapy with aggressive endoscopic management and short‐term surveillance in patients with localised IMT, with extirpative surgery reserved for refractory cases.