Multinucleate epidermal cells in non-neoplastic dermatoses.

Multinucleate epidermal cells (MEC) originated from keratinocytes were observed histologically in 92 of 197 cases of non-neoplastic dermatoses, such as lupus erythematosus (26 of 70), lichenoid eruptions (26 of 47), Hailey-Hailey disease (5 of 5), psoriasis vulgaris (20 of 49) and so on. Most of these cells had two nuclei, and a few had three nuclei. MEC usually showed perinuclear bands of eosinophilic material which also showed positive staining for epidermal fibres (tonofilaments). In all cases of Hailey-Hailey disease, close correlation between formation of MEC and dyskeratotic tendency was observed. From these findings, it is concluded that the mechanism of formation of MEC in these dermatoses may be similar to that of Bowen's disease, in which dyskeratotic tonofilaments become entangled with the spindles of the mitotic apparatus so that normal cell division cannot take place. It seems likely that MEC are a manifestation not only of malignant dyskeratosis but also of benign one.