Diffuse Alopecia Areata

Diffuse alopecia areata (AA) was identified as a distinct form of alopecia areata characterized by widespread scalp hair thinning rather than the typical patchy hair loss. It was a non-scarring condition that posed diagnostic challenges. The pathophysiology was not fully understood, but it was thought to involve an autoimmune response targeting anagen stage hair follicles, potentially affecting melanocytes, dermal papilla cells, and keratinocytes. Diffuse AA was noted for its intense inflammation and rapid progression compared to patchy AA, with inflammatory infiltrates including mononuclear cells, eosinophils, CD3+ T cells, and CD8+ T cells.