This 45-year-old man developed multiple minimally pruritic greyish brown papules and plaques on exposed areas of the skin over the last six months. The eruption was distributed over the scalp, face, neck and the tops of hands. Larger plaques on the sun exposed areas had an annular configuration with depressed hyperpigmented centers and red to violaceous borders. Over the last month lesions began to spread to sun protected sites. Actinic lichen planus (ALP), a variant of lichen planus, is also known as lichen planus tropicus, lichen planus subtropicus, lichenoid melanodermatitis, lichen planus atrophicus annularis, and summertime actinic lichenoid dermatitis. Three clinical types of ALP have been described: annular, dyschromic, and pigmented. The most common form is the annular type which is characterized by the development of erythematous hyperpigmented plaques with an annular configuration affecting the sun exposed areas of skin. Although the exact etiology of ALP remains unknown, sunlight appears to be the major precipitating factor. Pruritus and the Koebner phenomenon are typically absent. The eruption usually appears during spring and summer, and improvement or complete remission may occur during the winter, leaving hyperpigmented patches.
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symmetric, multiple, greyish brown papules and annular plaques.