Digital quantitative analysis of mast cell infiltration in interstitial cystitis

Aims To evaluate the significance of mast cell infiltration in interstitial cystitis (IC) by comparison with equally inflamed controls using a digital quantification technique. Methods Bladder biopsy specimens from 31 patients with Hunner type IC and 38 patients with non‐Hunner type IC were analyzed. Bladder biopsy specimens from 37 patients without IC, including 19 non‐specific chronic cystitis (“non‐IC cystitis”) specimens and 18 non‐inflamed bladder (“normal bladder”) specimens, were used as controls. Mast cell tryptase‐, CD3‐, CD20‐, and CD138‐immunoreactive cells were quantified using digital image analysis software to evaluate both mast cell and lymphoplasmacytic cell densities. Mast cell and lymphoplasmacytic cell densities were counted independently in the entire lamina propria and detrusor areas and compared among the four groups. Results In the lamina propria, there were no significant differences in mast cell and lymphoplasmacytic cell densities between Hunner type IC and non‐IC cystitis or between non‐Hunner type IC and normal bladder specimens. In the detrusor, the mast cell densities were not significantly different among the four groups. Mast cell density was correlated with lymphoplasmacytic cell density, but not with clinical parameters. Conclusions Mast cell density is not significantly different between IC specimens and non‐IC control specimens with a similar degree of background inflammation. The intensity of mast cell infiltration generally correlated with that of lymphoplasmacytic cells. We conclude that mast cell count is of no value in the differential diagnosis between IC and other etiologies.