DermatologyTier 2Disease (DEADMAN)

Alopecia areata

Description

Alopecia areata - an autoimmune condition causing non-scarring, typically well-demarcated patchy hair loss - from a T cell-mediated attack on the hair follicle that disrupts the normal growth cycle without destroying the follicle itself (hence its non-scarring, potentially reversible nature)

Relatively common, can occur at any age but often begins in childhood/young adulthood; associated with other autoimmune conditions (autoimmune thyroid disease, vitiligo) more often than in the general population

Autoreactive CD8+ T cells target the hair follicle, disrupting the anagen (growth) phase and causing affected follicles to prematurely enter the resting/shedding phase - since the follicle structure itself is preserved (unlike scarring alopecia), regrowth is possible, distinguishing the prognosis fundamentally from scarring alopecias

Well-demarcated, round/oval patches of hair loss with a smooth, non-scarring scalp surface; "exclamation mark" hairs (short hairs tapering toward the scalp) at the patch margin are a characteristic sign of active disease
Clinical diagnosis in most cases; biopsy occasionally needed to distinguish from scarring alopecia (cicatricial) when the diagnosis is uncertain
Alopecia totalis (complete scalp hair loss) and alopecia universalis (complete body hair loss) represent more extensive, severe disease patterns

Mild, limited disease may be observed given the possibility of spontaneous regrowth; intralesional corticosteroid injection is a common first-line active treatment for limited patches
JAK inhibitors (e.g. baricitinib) have emerged as an effective systemic treatment for more extensive disease, reflecting the T cell/cytokine-driven pathogenesis
Psychological support/counselling is an important component of management given the significant cosmetic and psychosocial impact, independent of the specific medical treatment chosen

Autoimmune thyroid disease, vitiligo, atopic disease (a weaker association), psychosocial/psychological impact of visible hair loss

Because the hair follicle structure is preserved (non-scarring), regrowth remains possible even after prolonged hair loss - this distinguishes alopecia areata's prognosis fundamentally from scarring alopecias, where follicle destruction makes regrowth impossible regardless of treatment

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