Comparison of Demographic and Photobiological Features of Chronic Actinic Dermatitis in Patients With Lighter vs Darker Skin Types

Abstract

Importance: Chronic actinic dermatitis (CAD) is classically described in older, white men, although increasing reports describe younger patients with darker skin types, particularly South Asians. Photocontact allergy occurs in CAD but is less studied than contact allergy in this exquisitely photosensitive condition.

Objective: To evaluate for differences in demographic and photobiological features between persons with darker and lighter skin types who have CAD.

Design, setting, and participants: This retrospective review included 70 consecutive adult patients (≥18 years) undergoing investigation for photosensitivity who were diagnosed with CAD from November 1, 2000, through August 31, 2015, at the specialist Photobiology Unit of a tertiary academic referral center.

Main outcomes and measures: Patient age, sex, ethnicity, clinical features, and phototesting outcomes.

Results: A total of 70 patients (37 men [53%] and 33 women [47%]; mean [SD] age, 50.9 [2.3] years) were diagnosed with CAD. Of these, 36 were non-Hispanic and non-Latino white, 31 were Asian (including 24 South Asian, 4 East Asian, and 3 Middle Eastern), and 3 were black. Patients were aged 9 to 83 years at diagnosis, with a mean (SD) age at onset of 42.6 (2.4) years and duration of disease of 8.8 (1.3) years. Forty-one had lighter skin types (Fitzpatrick skin types I-IV), and 29 had darker skin types (Fitzpatrick skin types V and VI). Patients with darker skin types and CAD were younger at diagnosis (mean [SD] age, 40.7 [3.5] vs 58.1 [2.5] years; P < . 001) and had earlier onset of photosensitivity (mean [SD] age, 35.5 [3.9] vs 47.5 [2.9] years; P = .01) compared with patients with lighter skin types. Of note, the male to female ratio in the lighter skin group was 2:1 compared with 1:2 in the darker skin group. Phototest reactions were equally severe in Fitzpatrick skin types V to VI and I to IV, with minimal erythemal doses to monochromatic UV-B, UV-A, and visible radiation and broadband provocation testing showing similar results. Photoallergic contact reactions to UV filters, personal sunscreen products, and nonsteroidal anti-inflammatory drugs were seen in both groups; 14 of 61 patients (23%) undergoing photopatch testing showed positive photopatch reactions.

Conclusions and relevance: Chronic actinic dermatitis presents with an earlier age at onset and an inverted male to female ratio in patients with darker compared with lighter skin types. Clinicians should thus be cognizant of CAD in younger women with darker skin types. Photopatch testing should be considered in patients with CAD, with coexistent photocontact allergy occurring in a substantial proportion.

Figure 1.. Clinical and Photobiological Features of Chronic Actinic Dermatitis

Photodistribution of eczema (A and B) and positive provocation test results (C and D) in a white and a South Asian patient. Monochromator phototesting (E and F) shows that markedly reduced minimal erythemal doses in light skin whereas darker skin erythema is less visible but raised lesions are evident. Positive photocontact reaction in a white patient (G).

Figure 2.. Action Spectrum of Chronic Actinic Dermatitis in Darker and Lighter Skin Types

The graph depicts patients with reduced minimal erythemal doses (MEDs) at each wave band on monochromator phototesting ± half-maximum bandwidth (300 ± 5, 320 ± 10, 330 ± 10, 350 ± 20, 370 ± 20, 400 ± 20, 500 ± 20, and 600 ± 20 nm).