Histological evidence supports low anesthetic bladder capacity as a marker of a bladder-centric disease subtype in interstitial cystitis/bladder pain syndrome

Abstract

Introduction and hypothesis: Low anesthetic bladder capacity has been shown to be a biomarker for bladder-centric interstitial cystitis/bladder pain syndrome (IC/BPS). The goal of this study was to determine if histopathological evidence from bladder biopsies supports anesthetic bladder capacity (BC) as a marker to distinguish a bladder-centric IC/BPS subtype.

Methods: From a review of our large IC/BPS cohort of patients undergoing hydrodistention, we identified a total of 41 patients with low BC (≤ 400 ml); an additional 41 consecutive patients with BC > 400 ml were selected as the comparator group. The original bladder mucosal biopsy pathology slides were re-reviewed by a single pathologist (blinded to patient information) using a standardized grading scale developed for this study.

Results: Histologically, the low BC subjects exhibited higher levels of acute inflammation (p = 0.0299), chronic inflammation (p = 0.0139), and erosion on microscopy (p = 0.0155); however, there was no significant difference in mast cell count between groups (p = 0.4431). There was no significant gender difference between the groups; female patients were the majority in both groups (low BC: 94.12%, non-low BC: 100%; p = 0.1246). Individuals in the low BC group were older (p < 0.0001), had a higher incidence of Hunner's lesions on cystoscopy (p < 0.0001), and had significantly higher scores, i.e., more bother symptoms, on two IC/BPS questionnaires (ICPI, p = 0.0154; ICSI, p = 0.0005).

Conclusions: IC/BPS patients with low anesthetic bladder capacity have histological evidence of significantly more acute and chronic inflammation compared with patients with a non-low bladder capacity. These data provide additional evidence to support low bladder capacity as a marker of a distinct bladder-centric IC/BPS phenotype.

Keywords: Bladder capacity; Bladder pain syndrome; Histology; Interstitial cystitis; Subtype.

Figure 1 -

Bladder biopsy tissue was collected from IC/BPS patients during hydrodistention under anesthesia and stained with H & E. Representative images that highlight some of the definitions set forth in scoring criteria are presented here. Panel a-c illustrates examples of mild, moderate, and severe chronic inflammation. Panel d (at 400X) illustrates the multi-lobulated nuclei of the neutrophils which are present in acute inflammation, as compared to the plasma cells and lymphocytes seen with chronic inflammation (Panel a-c). Panel e represents erosion seen on microscopy as an absence of the superficial layer of cells (solid red arrow) as compared the transitional cells seen on the right side of the image (blue dotted arrow).