[BLADDER PAIN SYNDROME - DOES DETRUSOR MASTOCYTOSIS PREDICT SYMPTOMATIC IMPROVEMENT FOLLOWING BLADDER HYDRODISTENTION...

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.

To determine whether detrusor mastocytosis can serve as a prognostic marker for treatment response and improvement duration.

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.

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).

Mastocystosis defines a discernible phenotype of IC/BPS, which exhibits higher rates and longer duration of hydrodistention treatment response.

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.