Skin manifestations in autoinflammatory syndromes.
Autoinflammatory diseases encompass a group of inflammatory diseases that are non-infectious, non-allergic, non-autoimmune and non-immunodeficient. The term was initially coined for a small group of familial periodic fever syndromes of which familial Mediterranean fever (FMF) is the most common and best known. Genetic and molecular analyses demonstrated for the majority of these diseases an impairment of inflammasomes to cause an increased activity of an interleukin-1-dependent inflammatory response. Over the last years an increasing number of either rare hereditary syndromes or acquired common diseases could be summarized under the designation of autoinflammatory disease, thus creating an emerging new rubric of inflammatory diseases. Many of them display cutaneous manifestations as both concomitant or more rarely main symptoms. To name some of them like erysipelas-like erythema in FMF; urticaria-like rashes in tumor necrosis factor receptor 1- or cryopyrin-associated periodic syndromes (TRAPS, CAPS), hyperimmunoglobulin D syndrome (HIDS) or Schnitzler syndrome; pyoderma gangrenosum and acne in PAPA syndrome; or behçetoid aphthous ulcerations in HIDS and PFAPA syndrome. Based on the new insights into pathogenesis one increasingly realizes the good response of these diseases to IL-1 antagonist therapies.