[Light and electron microscopy of primary localized cutaneous amyloidosis]

The two polar types of primary cutaneous amyloidosis are characterized by different alterations of the epidermis, i.e., epidermal hyperplasia and hyperkeratosis in lichen amyloidosus, hyperpigmentation without any essential epidermal changes in macular pigmented amyloidosis. Biopsies from six patients suffering from lichen amyloidosus and macular pigmented amyloidosis were examined light- and electron-microscopically to provide any information that could account for the different epidermal behavior in these two polar forms of primary cutaneous amyloidosis. No ultrastructural alterations were found that could be regarded as pathognomonic for one or the other form. Although in lichen amyloidosus alterations on keratinocytes seemed to be more pronounced than in macular pigmented amyloidosis, which, in contrast, shows stronger alterations of the basal membrane and the pigmentary system, these findings do not satisfactorily elucidate the histological and clinical differences between these most frequently occurring representatives of primary cutaneous amyloidosis.