In AA, there is a breakdown of these protective mechanisms.9,10 The cause of this breakdown is not fully understood but may involve genetic and environmental factors. These factors inhibit the secretion of immune privilege guardians and activate immune cells (mostly CD8+ T cells and CD4+ T cells, mast cells, natural killer cells, and dendritic cells), leading to the loss of immune privilege. The activated immune cells stimulate the production of interferon gamma (IFNgamma), which upregulates the expression of MHC-Ι and proinflammatory cytokines (IL-2, IL-4, and IL-15). The IFNgamma-driven inflammation is mediated by Janus kinase (JAK).11 The activated immune cells infiltrate the HF bulb like a "swarm of bees," shifting the HF into a premature catagen phase, followed by dystrophy, apoptosis, and hair loss9,10 (Figure 1c). The bulge area of the HF is not affected by this immunologic insult, thus allowing for hair regrowth.
How is alopecia areata diagnosed?
Alopecia areata is diagnosed clinically.4 A history of patient-reported patchy hair loss and regrowth highly indicates AA. In most cases, further tests are not required, although dermoscopy (also known as trichoscopy) may be used to validate the diagnosis. Salient dermoscopy features of AA include the presence of yellow dots, black dots, broken hairs, exclamation point hairs, and short vellus hairs (a sign of early regrowth). Skin biopsy for histopathology evaluation, fungal culture, or serology for other autoimmune diseases or infectious diseases is rarely necessary for diagnosing AA, except when clinical findings are inconclusive and to rule in or out other causes of hair loss.4
What are some of the causes for delay in alopecia areata diagnosis and treatment?
Usually, these patients are diagnosed. They are not treated, which is different. A retrospective analysis of administrative claims data from more than 68000 patients showed that only 25% were prescribed treatment within 7 days of an AA diagnosis, and 44% were not prescribed any treatment in the year following diagnosis.12 Our patient survey findings were consistent with these data; despite the majority of patients reporting hair loss often or all the time and significant psychosocial impact, 52% had never been treated, 30% were not aware that AA treatments exist, and 22% had not been referred to a specialist.
