Alopecia Areata

Alopecia areata is an immune-mediated form of non-scarring hair loss in which T cells attack hair follicles, abruptly pushing them out of the growth phase. It typically presents as one or more smooth, round bald patches on the scalp, but can involve eyebrows, beard, or any hair-bearing site, and in severe forms progresses to total scalp loss (alopecia totalis) or total body loss (alopecia universalis). The follicle is not destroyed, so regrowth remains possible even after long periods. Triggers are incompletely understood; genetic susceptibility and associations with other autoimmune conditions (thyroid disease, vitiligo, atopy) are well documented. Diagnosis is clinical, and treatment — topical or injected corticosteroids, immunotherapy, or JAK inhibitors for extensive disease — is directed by a dermatologist.

• •Sudden round or oval bald patches with smooth skin
• •Exclamation-mark hairs (narrower at the base) at patch edges
• •Nail pitting or ridging in some patients
• •Itching or tingling preceding loss in active patches
• •Progression to total scalp or body hair loss in a minority

• •Autoimmune attack on anagen-phase hair follicles by cytotoxic T cells, with collapse of the follicle's normal immune privilege
• •Genetic susceptibility — family history in 10–20% of cases and specific HLA associations
• •Frequently reported antecedent emotional or physical stress, though causal evidence is weak
• •Association with other autoimmune conditions: thyroid disease, vitiligo, atopy

No modifiable root cause is established; the condition reflects an autoimmune diathesis. Evaluating and managing associated autoimmune disease (especially thyroid) is worthwhile but does not reverse the hair loss.