Histological comparison of morphea and lichen sclerosus et atrophicus.

Although lichen sclerosus et atrophicus at an early stage and morphea can be differentiated clinically and histologically, both diseases at a late stage present diagnostic difficulties. In this study, collagen and acid glycosaminoglycans in the skin of both morphea and lichen sclerosus et atrophicus were examined by polarization microscopy. Picrosirius red and Toluidine blue (pH 5.8) were used as stains. Under polarized light, the picrosirius red-stained collagen fibers appeared green in the papillary and reticular dermis of morphea, except the fibers immediately below the epidermis, which appeared orange yellow. In lichen sclerosus et atrophicus, the collagen fibers appeared green in the reticular dermis at both early and late stage. In the papillary dermis the fibers appeared orange at an early stage and greenish orange at a late stage. Toluidine blue-stained birefringence in morphea diminished in the presence of MgCl2 at 0.2 M, in lichen sclerosus et atrophicus in the presence of MgCl2 at 0.3 M. Histologically, there were some differences in epidermal changes between the two diseases; the epidermis was thick in morphea and thin in lichen sclerosus et atrophicus. This difference seems to relate to that in the fibers beneath the epidermis.