AAD Alopecia Areata Practice Guidelines

Overview / Definition Alopecia areata (AA) is a common autoimmune disorder that leads to non-scarring hair loss. It can present as localized patches of hair loss (alopecia areata), total scalp alopecia (alopecia totalis), or complete hair loss including body hair (alopecia universalis). The exact cause remains unclear, but it is thought to involve a complex interplay between genetic, environmental, and immunological factors. Epidemiology Alopecia areata affects approximately 2% of the general population at some point in their lives. It is more prevalent in individuals aged 20-40 years, but it can occur in individuals of any age, including children. The condition shows a slight male predominance. A family history of alopecia areata or other autoimmune diseases is common, indicating a genetic predisposition. Pathophysiology / Mechanism The pathophysiology of alopecia areata is primarily autoimmune. In AA, hair follicles are targeted by the body's immune system, specifically by T lymphocytes. These immune cells infiltrate the hair follicles, leading to hair loss. The triggers for this immune response are not well understood, but factors such as stress, viral infections, and certain environmental exposures may play a role. Genetic factors: Familial cases suggest a genetic component with associations to certain HLA types. Environmental triggers: Stressful life events and infections may precipitate or exacerbate the condition. Clinical Presentation Alopecia areata typically presents with one or more well-defined, round or oval patches of hair loss. The affected areas may show: Short, broken hairs at the margins of the patch (exclamation mark hairs). Normal or mildly erythematous skin beneath the patches. Potential nail changes, such as pitting or ridging in some patients. Clinical Pearl: The presence of nail involvement can correlate with a more severe disease course and may indicate a higher likelihood of relapse. Diagnosis / Workup The diagnosis of alopecia areata is pr