Armor-like chronic actinic dermatitis

The pathogenesis of chronic actinic dermatitis is not well understood, which is speculated to be a delayed hypersensitivity caused by light induction. It is found that immunological basis is involved, and the infiltrating cells in the dermis are mainly CD8+ cytotoxic inhibitory T cells. They tend to occur in areas exposed to sunlight. A 68-year-old male presented with erythema infiltrating plaques on the frontal face for more than 5 years with pruritus. The skin is shaped like armor was diagnosed with armor-like chronic actinic dermatitis. The differential diagnoses may include seborrheic dermatitis, dermatomyositis, contact dermatitis. Topical use of a strong hormone cream may relieve symptoms, but the lesions are not completely resolved.