LICHEN-SCLEROSUS-ET-ATROPHICUS - A HISTOLOGICAL, IMMUNOHISTOCHEMICAL AND ELECTRON-MICROSCOPIC STUDY

We studied three cases of genital lichen sclerosus et atrophicus (LSA) using histological, immunohistochemical and ultrastructural technique s to elucidate the characteristics of the collagen fibres, the elastic fibres and the interfilamentous matrix in the upper dermal homogeneou s zone. In the early stages of LSA, the homogeneous zone caused elauni n fibres to push downwards and partially disappear, the collagen fibre s were presumably phagocytosed by fibroblasts, and there were peculiar cells containing numerous vacuoles in the cytoplasm. In the advanced stages of LSA, the homogeneous zones showed newly formed collagen fibr es and amorphous, dispersed, medium electron-dense substances that wer e probably composed of elastin or elastin-like substances and microfil aments originating from the collagen fibres. Immunohistochemically, th ere were numerous anti-aortic alpha-elastin-positive substances, but t here was no positivity for anti-amyloid P component. These findings su ggest that in advanced LSA a hybrid substance (elastocollagenous mass) between collagen fibres and elastic fibres may be formed in the homog eneous zone.