Immunohistochemical evidence of skin immune system involvement in vulvar lichen sclerosus et atrophicus.

Biopsies taken from vulvar lesions in 12 women affected by vulvar lichen sclerosus et atrophicus (LSA) have been processed for immunohistological study. Activated (HLA-Dr+) T cells, associated with CD1a+ accessory cells, were found in the dermis in all cases, with architectural patterns varying in relation to the histological phase (early, well developed, old) of the lesion. Interestingly, the number of epidermal CD1a+ Langerhans cells (LCs) was increased in all cases, without any correlation with the amount of the dermal infiltrate and with the histological phase of the lesions. In fact, also in old lesions the number of epidermal CD1a+ LCs was increased, and the sparse dermal lymphoid cells showed a persistent HLA-Dr antigen expression. These data, indicating the persistent activation of epidermal antigen-presenting cells and lymphoid cells in all the evolutive phases of vulvar LSA, suggest a possible involvement of the skin immune system in the pathogenesis of LSA.