APremilast After FumaRic Acid Ester Treatment

Inclusion Criteria: * Adult patients ≥18 years * Moderate to severe plaque-type psoriasis according to SmPC * Phase I: Patients will be included once they are started on systemic fumaric acid esters (e.g. Fumaderm initial®) for the treatment of moderate-to-severe psoriasis vulgaris. Patients initiated on fumaric acid esters will be followed for a maximum of 24 weeks during phase I. Patients continued on fumaric acid esters beyond 24 weeks or switched to a therapy other than apremilast during or at the end of the 24-week phase I period will no longer be followed. * Phase II: Patients switched to apremilast during or at the end of the 24-week phase I period will be included in phase II and followed for additional 32 weeks. * Written informed consent Exclusion Criteria: * Prior treatment with biologics * According to SmPC * Participation in another clinical trial (parallel inclusion in the National psoriasis registry PsoBest is allowed)