Alopecia Areata: From Pathogenesis to Diagnosis & Treatment

Alopecia areata (AA) is a common, inflammatory, nonscarring hairloss disease characterized by an autoimmune response to anagen hair follicles (HFs). It affects up to 2% of the general population with variations in the clinical presentation, ranging from small, well-circumscribed patches of hair loss to a complete absence of body and scalp hair. Accumulated evidence suggests that collapse of the HF immune privilege after triggering event leads to autoimmune response in which autoreactive cytotoxic CD8+NKG2D+ T cells mainly target exposed HF autoantigens. Multiple genetic and environment factors contribute to the pathogenesis of AA. The available treatments for AA include corticosteroids and other immunomodulators, minoxidil, and contact immunotherapy. Recent insights into the pathogenesis of AA have led to the development of new treatment strategies, such as Janus kinase (JAK) inhibitors, biologics, and several small molecular agents.