Chronic Actinic Dermatitis: a Review

Purpose of Review To update readers on the current understandings of chronic actinic dermatitis (CAD) in regard to epidemiology, clinical findings, pathophysiology, treatment, and prognosis. Recent Findings CAD is classically thought to be primarily a disease of elderly Caucasian males, though recent evidence suggests that in skin of color, the disease manifests more often in younger females. Recent studies suggest the pathogenesis of CAD involves a type-IV hypersensitivity reaction, similar to allergic contact dermatitis. There is also evidence of resistance to UV-induced immunosuppression in these patients, similar to polymorphous light eruption (PMLE). Furthermore, a lower CD4/CD8 ratio on flow cytometry in CAD patients has been correlated with increased tissue burden of disease. Photoprotection remains a mainstay of treatment, though recent evidence suggests potential efficacy of tofacitinib or short courses of narrowband UVB phototherapy as treatment options. Summary CAD is an immunologically mediated photodermatosis characterized by pruritic eczematous lesions of sun-exposed areas, most commonly seen in older Caucasian males. While the pathogenesis of the condition is not fully understood, a type-IV hypersensitivity reaction to UV-induced neoantigens is thought to play a role. Photoprotection remains the mainstay of treatment, though adjunctive treatments are rapidly emerging. Though considered a chronic condition, CAD tends to improve over time.