Erythrokeratodermia variabilis: immunohistochemical and ultrastructural studies of the epidermis.

Immunohistochemical and ultrastructural study of the epidermis was performed in a 53-year-old female with erythrokeratodermia variabilis (EKV) before and after treatment with the aromatic retinoid Etretinate (RO 10-9359). Aberrant expression of cytokeratin PKK2 (Labsystems, Helsinki, Finland) in lesional EKV stratum corneum was observed; this feature disappeared after Etretinate therapy. A normal distribution of DR-positive dendritic Langerhans' cells was seen in diseased, control and post-treatment skin specimens. The striking finding of this study was thus the shift to a basal cell-type keratin reactivity in stratum corneum in lesional skin, perhaps a reflection of cytoskeleton features related to cell adhesion. Increased adhesion between the cells in stratum corneum might account for the retention type of hyperkeratosis characteristic of EKV.