Exploring adult-onset actinic prurigo in Thailand

Actinic prurigo (AP) is an uncommon photodermatosis. In European and native American populations, AP is more frequently found in young women and shows clinical improvement or remission in adulthood. The clinical symptoms of AP in Asians differ in that the condition usually occurs in adults (adult-onset AP) and is clinically persistent. The objective of this study is to investigate the characteristics and outcomes of patients with AP in Thailand. A total of 15 cases diagnosed AP were reviewed. All cases were adult-onset AP (mean age of onset was 45.5 years). Male predominated (66.7%). Mostly of them presented with papules on face and upper extremities. Mucositis was presented in 2 patients. Phototesting revealed decreased MED for UVA alone in 3 patients and decreased MED for both UVA and UVB in 3 patients. Nine patients who had normal MED were further performed photoprovocation test and showed positive UVA photoprovocation in 5 patients; positive both UVA and UVB photoprovocation in 4 patients. Systemic immunosuppressant was prescribed in 60% of patients. Median time to clinical improvement was 8.6 months. Complete clinical remission was found in only 3 patients. Adult-onset AP has different clinical features and responds differently to treatment, compared to classical AP.