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, < or =5.6 mJ x 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.