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In PS, the immature DCs are mostly lag/langerin + Langerhans cells (LCs). In the epidermis of PS, LCs predominate over fully mature DCs (non-LC type, CD83+, DC-lamp+). In the dermis of PS and TS, equal numbers of mature and immature (CD1a+, CD1c+) DCs are densely interspersed between the lymphocytic infiltrate. In TS, immature DCs mostly lack lag or langerin expression. Immature DCs with incorporated apoptotic cells were found rarely in PS but increasingly in TS. By triple staining in situ we could now show that strongly IL-10+ cells frequently surround immature DCs, some of them with incorporated apoptotic cells. CONCLUSIONS; DCs in MF perform a dual role, namely induction and maintenance of antitumour immunity, or, under less favourable circumstances such as production of IL-10 downregulation of antitumour immunity. The latter condition was mainly seen in TS, possibly explaining disease progression. Further in vitro studies are now required illuminating the role of DCs for the antitumour immune response in MF.

Our findings differ from those of previous studies, showing a lower rate of family history and a higher incidence of severe psoriasis. Differential diagnosis should be made especially when lesions occur at the scalp, elbow or balanus. Allergic contact dermatitis takes place more frequently in children with psoriasis than in normal children. Systemic corticosteroids should not be routinely used and other safer and more effective treatments are needed for severe cases.