Expression of p53 and proliferating cell nuclear antigen in lichen sclerosus et atrophicus with different histological features.

In this study, immunohistochemistry was used to investigate p53 and proliferating cell nuclear antigen (PCNA) expression in 40 cases of lichen sclerosus et atrophicus (LSA). Nuclear immunoreactivity for both p53 and PCNA was found in the basal and parabasal keratinocytes in the majority (91%) of the lesions. Typically, there was a widely varying positivity for PCNA, suggesting a wide range of proliferative capacity in individual LSA lesions. Lesions with p53 positivity in 5% or more of the basal cells also presented a strong (> 14% of basal cells positive) PCNA positivity (p = 0.030) and exhibited a higher mitotic rate (p = 0.002), suggesting a causal relationship between enhanced p53 expression and elevated cell proliferation. Lesions with a low number of PCNA-positive cells (< 15% of basal and parabasal cells positive) exhibited a wider subepithelial edematous zone and a thinner epithelium than in the lesions with a higher number of PCNA-positive cells. The results show that later stages of LSA, typified by subepithelial edema and epithelial atrophy, are associated with decreased proliferative activity of the basal and parabasal cells.