Inflammatory features of melasma lesions in Asian skin

Melasma is triggered by various factors including ultraviolet radiation and estrogen; however, its pathogenesis is unclear. To investigate the inflammatory features of melasma lesions as triggers for this disorder, 197 women with melasma who attended Asan Medical Center and Kangskin Clinic, Seoul, from June 2011 to October 2011 completed a questionnaire concerning triggering or aggravating factors. These cases were divided into "non-inflammatory" and "inflammatory" groups. Skin biopsies and immunostaining for CD68, CD117, and leukocyte common antigen (LCA) were performed in the lesional and peri-lesional skin of ten cases in the non-inflammatory group and nine cases in the inflammatory group. Among the 197 subjects (mean age, 41.5 years; mean age of melasma onset, 33.8 years), 50 patients (25.4%) were categorized into the inflammatory group. This group comprised cases that had inflammatory symptoms and events that triggered the melasma lesions. The lesional dermis contained more CD68(+) melanophages, CD117(+) mast cells, and LCA(+) leukocytes in the inflammatory group than in the non-inflammatory group. Inflammatory clinical features and an increased number of inflammatory cells in the lesion may be involved in the development of melasma in Asian skin.