[BLADDER PAIN SYNDROME - DOES DETRUSOR MASTOCYTOSIS PREDICT SYMPTOMATIC IMPROVEMENT FOLLOWING BLADDER HYDRODISTENTION UNDER ANESTHESIA?]

INTRODUCTION Interstitial cystitis/bladder pain syndrome (IC/BPS) is a chronic, debilitating syndrome involving bladder pain and lower urinary tract symptoms (LUTS), with a substantial effect on patients' quality of life. IC/BPS poses a diagnostic challenge, and its available treatment options remain only moderately effective. Bladder-wall biopsies from IC/BPS patients commonly uncover mastocytosis. While mast-cells are suspected as pivotal in disease pathogenesis, the clinical significance of their presence remains unclear. Clinical guidelines differ on whether or not bladder biopsies should be a part of routine IC/BPS workup. AIMS To determine whether detrusor mastocytosis can serve as a prognostic marker for treatment response and improvement duration. METHODS We retrospectively collected patient data for IC/BPS patients who underwent bladder hydrodistension under anesthesia. We used statistical modelling to determine the effect of mastocystosis and other possible predictive factors - age, comorbidity, Hunner lesions - on the presence and duration of symptom improvement. RESULTS A total of 35 patients (89% female, median age 63.5 [IQR 48.8-73.6] years) underwent hydrodistension, of whom 28 (89% female, median age 63.0 [44.8-73.1] years) had bladder biopsies; 11 (39%) of them had mastocystosis. Within a median follow-up of 8.8 [1.7-24.2] months, 11 (100%) of the patients with mastocytosis and 9 (53%) of the patients without it, experienced symptomatic improvement (p=0.007). Improvement duration was 8 months longer (p=0.006) in those with mastocystosis. Univariate logistic regression models were used to estimate odds ratios (OR). Mastocytosis (p=0.004) and Charlson Comorbidity score were the only variables with a statistically significant OR. Univariate survival models were fitted, and improvement duration was estimated to be longer in patients with mastocystosis (p=0.01). A multivariate Cox regression model found no variable to be statistically significant, though mastocystosis was borderline significant (p=0.055). CONCLUSIONS Mastocystosis defines a discernible phenotype of IC/BPS, which exhibits higher rates and longer duration of hydrodistention treatment response. DISCUSSION Notwithstanding limitations of sample size and retrospective study design, we were able to demonstrate that mastocystosis can serve as a prognostic factor for symptom improvement after hydrodistension in IC/BPS patients. Prospective studies are required to validate this finding and to investigate the mechanisms involved.