The objective of the study is to explore various clinical and biochemical parameters and their potential associations with disease severity, activity, and prognosis in atopic dermatitis, psoriasis, alopecia areata, and vitiligo. Further, the study aims at validating remote assessments of skin lesions, using smartphone-acquired photos. The study will also assess the feasibility and compliance with weekly remote-assessments and patient-reported data collection over the full study period of one year. The study will observe patients through a period of one year and will provide detailed information concerning the type and dose of medication used, as well as data to evaluate the disease activity with high resolution during this period. The study will involve collection of serum samples for exploratory biomarkers, and punch biopsies. A total of approximately 370 patients, divided into the four disease areas of atopic dermatitis, alopecia areata, psoriasis, and vitiligo, will be enrolled in the study. Using a combination of self-reported and on-site assessments and procedures, the intent is to observe the natural history of patients with select dermatological conditions, investigate tissue characteristics associated with disease activity and symptoms, and evaluate the validity of remote assessment of lesions, and feasibility of weekly self-acquired smart-phone images of skin lesions for remote assessment.