Skin disorders in patients with primary immunodeficiencies

Primary immunodeficiencies (PIDs) are conditions caused by molecular defects in the genes required for normal immune function. PIDs are rare, with a prevalence of approximately 1 in 25,000. Though much remains to be explored in the field of PIDs, over 185 distinct defects have been described. Infections are generally the most pronounced feature of PIDs. However, PIDs have many non-infectious sequelae also. Cutaneous involvement, infectious and non-infectious, is prominent in many cases. In fact, cutaneous manifestations precede immunologic diagnosis in 79 % of PID patients. PIDs are subject to wide clinical, immunological, and genetic heterogeneity. Different mutations in the same gene may yield variable phenotypes. This chapter will detail the clinical manifestations, genetics and pathophysiology, diagnosis, and management of selected PIDs with a special focus on those with historically prominent cutaneous findings.