Mast cells and nerve fibers in interstitial cystitis (IC): an algorithm for histologic diagnosis via quantitative image analysis and morphometry (QIAM).

OBJECTIVE To develop and evaluate a diagnostic algorithm based on the alteration of mast cell and nerve fiber observed in bladder tissue of patients with interstitial cystitis (IC). MATERIALS AND METHODS Non-IC samples from 6 control groups (N = 10, 10, 13, 2, 11, and 3, respectively) and nonclassic interstitial cystitis (NC-IC, N = 20) were stained with Giemsa stain in order to calculate the detrusor to mucosa mast cell ratio (DMMCR) using quantitative image analysis and morphometry (QIAM). Immunohistochemical staining for S-100 protein was also performed to quantify nerve fiber proliferation in the detrusor muscle of the bladder. RESULTS The average DMMCR of NC-IC was 1.19. Bacille Calmette-Guérin (BCG) cystitis was 0.84 and microscopically normal bladder tissue from patients with bladder or prostate cancer was 0.45. No case of IC that we examined had a DMMCR < 0.5. The number and percentage area of nerve fibers in the detrusor in IC were increased compared to controls and BCG (IC, 2.01%; BCG, 0.95%; control, 1.3%). CONCLUSION A diagnostic algorithm is proposed for IC based on the findings that indicate that: 1) if the DMMCR > 0.75, then IC is present; 2) if the DMMCR < 0.5, then IC is negative; and 3) if the DMMCR is between 0.5 and 0.75, a quantitative S-100 protein staining analysis can be employed to evaluate nerve fiber proliferation to detect those marginal cases of NC-IC. The findings of the study also suggest that a neuroimmune process or mediation may be involved in the pathogenesis of IC.