The natural history of chronic actinic dermatitis

Objective: To determine the prognosis for resolution of abnormal cutaneous photosensitivity in patients with chronic actinic dermatitis (also known as the photosensitivity dermatitis and actinic reticuloid syndrome). Design: Historical cohort study involving follow-up of patients for up to 24 years from diagnosis. Setting: A Scottish tertiary referral center for investigation of photodermatosis. Patients: One hundred seventy-eight patients with chronic actinic dermatitis, 62% of a cohort of 285 living patients identified in the Photobiology Unit database. Interventions: Recall for repeated clinical assessment and monochromator phototesting. All patients underwent patch testing when initially assessed; this was repeated at follow-up in a subgroup of patients. Main Outcome Measures: Resolution of abnormal photosensitivity, defined as clinical resolution and return of phototest responses to within normal population limits. In addition, possible prognostic factors for resolution of photosensitivity were examined. Results: The probability of abnormal photosensitivity resolving by 10 years from diagnosis is 1 in 5. Particularly severe abnormal UV-B photosensitivity (minimal erythema dose at 305 +/- 5 nm half-maximum bandwidth, less than or equal to 5.6 mJ . cm(-2)) and the identification of separate contact allergens in 2 or more patch test batteries are predictors of a poorer prognosis for resolution. Loss of contact allergies was not associated with a different prognosis for photosensitivity resolution. Our findings probably underestimate the probability of resolution, as those referred to a tertiary referral center and willing to attend for follow-up may include a disproportionate number of severely affected patients. Conclusions: Newly diagnosed patients can be told that most of them will improve with appropriate UV/visible light and allergen avoidance and that there is hope that their photosensitivity will completely resolve.