Abstract: Objective: To detect the level of inducible nitric oxide synthase (iNOS) and endothelial nitric oxide synthase (eNOS) in lichen simplex chronicus (LSC) and lichen sclerosus (LS). Methods: The level of iNOS and eNOS in 30 LSC samples and 30 LS samples and 10 normal samples were detected by immunohistochemistry SABC method. Microvessel density (MVD) was detected through staining for CD34. Results: No expression of iNOS and eNOS was detected in normal skin. The mean numbers of positive cells per field of vision of iNOS and eNOS in LSC samples were 14.83±3.79 and 17.86±4.82, which were higher than those in LS (8.00±3.35 and 6.43±3.87), with significant differences (P＜0.05). The levels of MVD in LSC samples and normal skin were 21.58±2.48 and 20.44±3.66, which were higher than that in LS (10.34±2.83). The expression of iNOS was positively correlated with eNOS (Kappa=0.811, P＜0.05). Conclusion: iNOS and eNOS may participate in the inflammatory process of vasodilation in LSC samples. The number of capillaries is decreased and iNOS or eNOS may improve the blood transport of microcirculation compensatively. 

Key words: nitric oxide synthase, lichen simplex chronicus, lichen sclerosus, microvessel density