Actinic lichen planus

Actinic lichen planus, also known as lichen planus actinicus, lichen planus subtropicus, or summertime actinic lichenoid eruption, is a rare variant of lichen planus that occurs predominantly in sun-exposed areas of the skin. It is considered a photodistributed form of lichen planus and is most commonly reported in individuals living in tropical and subtropical regions, particularly in the Middle East, Africa, and the Indian subcontinent. The condition predominantly affects the skin, with lesions typically appearing on sun-exposed sites such as the face, dorsal hands, forearms, and the V-area of the neck. Clinically, actinic lichen planus presents as annular, nummular (coin-shaped), or plaque-like hyperpigmented to violaceous lesions, often with a characteristic rim of hyperpigmentation. Unlike classic lichen planus, the lesions may appear as dyschromic (dark brown to bluish) patches rather than the typical polygonal, pruritic, purple papules. Some patients experience mild itching, though the condition can also be asymptomatic. The lesions tend to worsen with sun exposure and may improve during winter months or with sun avoidance. Treatment of actinic lichen planus centers on strict sun protection, including the use of broad-spectrum sunscreens and protective clothing. Topical corticosteroids are commonly used as first-line therapy to reduce inflammation. Topical calcineurin inhibitors (such as tacrolimus), antimalarials (hydroxychloroquine), and topical retinoids have also been used with variable success. In more resistant cases, systemic treatments including oral corticosteroids or hydroxychloroquine may be considered. The condition may resolve spontaneously but can leave persistent post-inflammatory hyperpigmentation, which can be cosmetically distressing, particularly in individuals with darker skin tones.

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