Pustular psoriasis and related pustular skin diseases.

Patients with pustular psoriasis or related pustular diseases may have genetic abnormalities impairing the function of key players of the innate skin immune system. Recently, identification of these abnormalities has changed the paradigm of several of these diseases. These include generalized pustular psoriasis, palmoplantar pustular psoriasis and acrodermatitis continua of Hallopeau, and also drug-induced acute exanthematous generalized pustular eruption. Identified mutations in IL36RN, CARD14 and AP1S3 in different groups of patients lead to enhanced inflammatory cascade in several cellular subtypes including keratinocytes, and to the recruitment and activation of neutrophils and macrophages. These insights have unveiled pathophysiological features that shift the existing paradigms and emphasize the autoinflammatory nature of skin pustular disorders. They also highlight the crucial role of the innate immune system across entities belonging to the psoriasis disease spectrum, allowing identification of new appealing therapeutic targets.