More treatments for psoriasis have been introduced during the past 25 years than for all other diseases in dermatology combined. The impact of those treatments on all dermatologic disease has been profound. For example, psoralen–UV-A was introduced for psoriasis but has changed the treatment of cutaneous T-cell lymphoma.1 Narrowband UV-B was developed for psoriasis but has had a major impact on the treatment of vitiligo.2 Acitretin and its precursor etretinate were both approved for psoriasis but have found an important role in skin cancer prevention.3