Inclusion Criteria:  Psoriasis under systemic treatment for more than a year and in remission for at least 12 weeks: Physician Global Assessment [PGA] score 0-1, Psoriasis Area and Severity Index [PASI] score ≤ 3 OR inflammatory Bowel Disease [IBD] (Crohn's disease or ulcerative colitis) under systemic treatment for more than a year and in deep remission (clinical and endoscopic = SES CD 0-2 score for Crohn's, endoscopic Mayo score) in whom a de-escalation of treatment is scheduled. Agrrement of treatment discontinuation between patient and clinician before inclusion in this study. Informed Consent Form signed  Exclusion Criteria:  Uncertain diagnosis Local immunomodulatory treatment for psoriasis ongoing or stopped for less than three weeks