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.