Epidermal Langerhans' cells in patients with pustulosis palmoplantaris treated with etretinate or etretinate + methoxsalen photochemotherapy

Epidermal Langerhans' cells (LC) were studied in patients with pustulosis palmoplantaris (PPP) by utilizing the monoclonal antibodies anti-Leu6 and anti-HLA-DR in combination with an immunoperoxidase technique. In non-pustular areas of the skin lesions in PPP, an increased number of epidermal LC was found compared with control subjects. No change in LC counts was observed following etretinate monotherapy for 2 weeks. Etretinate was then combined with PUVA treatment of one palm/sole with the contralateral side as a non-UVA exposed control. After 6-12 weeks of etretinate + PUVA treatment the PPP had resolved and the number of epidermal dendritic HLA-DR+ and Leu6+ cells had normalized. On the contralateral side, etretinate treatment induced a marked clinical improvement and a reduction of HLA-DR+ cells. The observation of an increased LC population in active PPP and a reduction during clinical improvement indicates a close relationship between LC and the activity of PPP.