Skin manifestations of immunodeficiencies in children.

Immunodeficiency is a state in which the immune system's ability to fight infectious diseases is compromised or entirely absent. Most cases of immunodeficiency are acquired (secondary) but some people are born with defects in the immune system, or primary immunodeficiency. More than 140 distinct genes have been identified, which abnormalities account for more than 200 different forms of primary immunodeficiencies. The skin may be one of the organs involved in immunodeficiencies and in a number of primary immunodeficiency syndromes the skin is one of the main clues to the diagnosis and dermatologists may be the first to appreciate an immune defect in their patients. From "A" of well-known ataxia-telangiectasia to "Z" of recently identified zeta-chain (TCR) associated protein kinase 70kDa (ZAP-70) deficiency, this review attempts to provide a complete and up-to-date summary of all known primary immunodeficiencies featuring skin manifestations and presenting in the pediatric population. Given the vastness of the topic etiopathogenesis, extracutaneous manifestations, diagnosis, treatment and prognosis were not discussed unless briefly. We hope that this effort will help specialists to facilitate the recognition of primary immunodeficiencies and therefore early diagnosis and management.