Psoriasis treatment in difficult locations: scalp, nails, and intertriginous areas

Psoriasis comprises a broad spectrum of different clinical courses among which the chronic stable psoriasis by far occurs most frequently. The clinical presentation ranges from mild disease to more serious forms involving large areas of skin and/or joint disease. A number of modifying factors may impact on treatment choice in individual cases (eg, location of the lesions, disease phase, treatment history, response to previous treatments, comorbidity). Aside from this consideration, there are special localizations that remain some of the most difficult regions to control. Such entities are the scalp, nails, and intertriginous areas. Topical treatment of such different-to-treat areas has to be considered as a first-line intervention strategy, at least in those patients who are presenting an exclusively isolated involvement. In some situations (eg, in severe psoriasis or in patients who are refractory to topical treatment), however, a systemic treatment is indicated. Most obvious difficulties in treating these locations are due to unrealistic expectations from the patients' perspectives, time-consuming applications, side effects, cosmetic injuries, and restricted bioavailability of active compounds. Aside from hair care, initial use of keratolytics for scalp psoriasis, corticosteroids, and vitamin D3 and analogues are currently standard treatments. Recently developed new formulations of both active ingredients such as foam or gel appear to be more acceptable to patients than traditional creams or ointments. Current treatment options for nail psoriasis are very often poorly efficacious, associated with undesirable effects, or time consuming. Success has to be measured in terms of months. Topical treatments (eg, corticosteroids, vitamin D analogues, tazarotene) are mainly used, but impressive improvement rates mostly will be achieved by systemic treatment of conventional and biologic agents. Finally, the usefulness of corticosteroids, vitamin D and analogues, and calcineurin inhibitors in treating intertriginous psoriasis clearly is demonstrated. Especially the use of calcineurin inhibitors exhibits efficacy in intertriginous regions and therefore may be seen as a promising treatment option in the future. Besides the important innovations in the last years, there is a need for new effective and well-tolerated treatment modalities, especially for long-term use in the 3 difficult-to-treat locations, which encompass cosmetic acceptability.