Actinic lichen planus

Indurated plaques or papules erupt on the face, neck, and the dorsal surface of hands after exposure to ultraviolet (UV) light. Different morphological subtypes have been described: the classic form (violaceous papules), a granuloma annular-like form (annular erythematous hyperpigmented plaques), a dyschromic form (white angular coalescent papules on the neck and dorsa of the hands), and a pigmented melasma-like form (dark patches on the face and neck). There is no mucosal or nail involvement. Histology is characterized by more marked melanin incontinence than in classical lichen planus; there may also be a lighter inflammatory cell infiltrate and focal areas of parakeratosis.