Clinicopathologic Analysis of Inflammatory Myofibroblastic Tumors of the Urinary Bladder.

To describe clinical, imaging, and histopathologic characteristics of inflammatory myofibroblastic tumor (IMT) of the urinary bladder and provide initial management and surveillance recommendations.

We identified patients with IMT of the bladder treated at our facility from 1998-2020. Categorical variables were analyzed 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.

IMT was diagnosed in 35 patients with median follow-up of 20 months (interquartile range [IQR] 11.5-68.5 months). At initial diagnosis 86% were clinically organ-confined, 9% locally-advanced, and 5% metastatic. The rate of residual disease on restaging transurethral resection (TUR) was 92%. Of the 15 patients with organ-confined disease managed initially with TUR, 5 patients (33%) recurred at a median 5 months from initial diagnosis (IQR 3.0-5.5 months). 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 an initial 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 ALK translocation and achieved a durable complete remission with 7 months of crizotinib therapy.

No IMT recurrences were diagnosed beyond 6 months in patients who underwent aggressive endoscopic management, including restaging TUR. There were additionally no recurrences noted after definitive radical or partial cystectomy. These data support aggressive endoscopic management and short-term surveillance in patients with localized IMT, with extirpative surgery reserved for refractory cases.

BJU international. 2021 Nov 13 [Epub ahead of print]

Patrick J Hensley, Kelly K Bree, Charles C Guo, Niyati Lobo, Matthew T Campbell, Curtis A Pettaway, Ashish M Kamat

Department of Urology, MD Anderson Cancer Center, Houston., Department of Pathology, MD Anderson Cancer Center, Houston., Department of Genitourinary Medical Oncology, MD Anderson Cancer Center, Houston.

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