LAUSR

PURPOSE We identified a subset of patients with noninfectious cystitis who develop refractory symptoms marked by diffuse inflammatory changes, reduced bladder capacity, and vesicoureteral reflux (VUR), termed here as "progressive inflammatory cystitis" (PIC). Our objective was to describe the phenotype, disease outcomes, and pathologic findings of PIC. MATERIAL AND METHODS A single institution retrospective cohort study of patients with PIC. Patients with a history of pelvic radiation, urologic malignancy, or neurogenic bladder were excluded. We describe cohort characteristics and use bivariate analyses to compare subgroups. Kaplan-Meier methods estimate time to urinary diversion. RESULTS From 2008 to 2020, 46 patients with PIC were identified. The median age of symptom onset was 63 years old (interquartile range [IQR]: 56, 70) and the most common presenting symptoms were urinary urgency/frequency (54%) and incontinence (48%). Urodynamics showed a median maximum bladder capacity of 80 mL (IQR: 34, 152), commonly with VUR (68%) and hydronephrosis (59%). Ultimately 36 patients (78%) underwent urinary diversion at a median of 4.5 years (IQR: 2, 6.5) after symptom onset. Significant pathologic findings include presence of ulceration (52%), acute and chronic inflammation (68%), including eosinophils (80%), lymphoid follicles (56%), and mast cells in both lamina and muscularis propria (76%). CONCLUSIONS PIC is a newly defined entity characterized by significantly diminished bladder capacity, upper tract changes, and relatively quick progression to urinary diversion. Larger prospective cohort studies are required to further characterize this severe phenotype of chronic noninfectious cystitis, aid earlier diagnosis, and guide management decisions.