Podoplanin (D2-40) is a reliable marker of urinary bladder myofibroblasts (telocytes).

Podoplanin, D2-40, has been described in a variety of normal and neoplastic tissues. It is often used for highlighting lymphatics. We evaluated the expression of podoplanin in alpha-smooth muscle actin-positive myofibroblasts producing the suburothelial layer in tunica propria of the urinary bladder that have some similar features with telocytes. Our results showed that these cells demonstrate distinct D2-40 immunoreactivity from telocytes occurring in the renal pelvis and ureter. We observed positive reaction not only in bioptic specimens from women with interstitial cystitis, but also in a control group of women and men treated for pathological bladder lesion different from interstitial cystitis. It is interesting that identical staining reaction was observed in the ureters only exceptionally. In addition, we examined samples from myofibroblastic tumoriform lesions of soft tissue such as nodular fascitis and fibromatosis (desmoid) and we obtained negative results. It means that the so-called myofibroblasts of urinary bladder tunica propria have a unique immunophenotype that has probably not been described until now. Our findings suggest that D2-40 can be used as a complementary immunostainer to alpha-smooth muscle actin on urinary bladder biopsies from patients with interstitial cystitis. The role of D2-40 as an immunohistochemical marker is still being investigated.