Negative immunoperoxidase staining for lysozyme in nodular subepidermal fibrosis

Nodular subepidermal fibrosis (NSF) is a clinical entity, the histogenetic origins of which remain unclear. More than 200 such lesions were examined with light microscopy and subdivided into four types based on their relative degree of cellularity. Five examples of each subtype were stained for lysozyme with the peroxidase-antiperoxidase technique. None of the 20 lesions contained cells with lysozyme. We conclude that the basic cell type in NSF is not lysozyme-containing macrophage; it is a different cell, perhaps one of mesenchymal origin.