[Formation of dermo-epidermal hyperplasia in psoriasis]

Formation of hyperplastic dermal papillae in psoriasis was studied by radioautography after incorporation of tritiated thymidine, by planimetry and by scanning electron microscopy. At the border zone of a psoriatic plaque, hyperplastic dermal papillae result from a passive lengthening of dermal papillae. At the center of a psoriatic plaque, papillomatosis represents an active remodelling of the papillary dermis with destructions and neoformation of the basement membrane zone. The origin of these remodellings is presumably mechanical and related to forces exerted by the epidermis.