Vasculitis in lichen sclerosus: an under recognized feature?

To analyse 90 vulvar and 72 penile cases of lichen sclerosus (LS) on haematoxylin and eosin sections for vascular changes and the vascular infiltrates immunohistochemically with antibodies to T cells, B cells and antigen-presenting dendritic cells. LS is a skin disease of presumed autoimmune origin. Autoimmune diseases are mediated by lymphocytes which occasionally produce a lymphocytic vasculitis.

Three types of lymphocytic infiltrates were identified: (i) perivascular lymphocytic infiltrates without damage to vessel walls; (ii) lymphocytic vasculitis in three forms: (a) concentric lymphohistiocytic infiltrates with lamination of the adventitia by basement membrane material which was typical for penile LS; (b) lymphocytic vasculitis with dense perivascular lymphocytic cuffing with occasional fibrin deposition in vessel walls and subendothelial lymphocyte infiltration, quite common in vulvar LS; and (c) intramural lymphocytic infiltrates in large muscular vessels; (iii) leukocytoclastic vasculitis in LS was exceptionally rare. In lymphocytic vasculitis, CD20+ B cells, CD4+ T cells and dendritic cells were the principal infiltrating cells.

Dendritic cells capture (foreign) antigens after entry into the affected tissues and initiate immune responses acting as a matrix on which antigen-specific T and B cells interact. The described vascular features are indicative of antigen-mediated vasculitic changes in LS.