Microscopic examination of the biopsy specimen revealed thinning of the epidermis, hypergranulosis, and vacuolar degeneration of the basal cell layer. A bandlike lymphohistiocytic infiltrate was present in the upper dermis.
The patient was treated with a medium-potency topical corticosteroid and instructed to avoid sun exposure. The lesion resolved within 2 months, leaving a slightly depressed hyperpigmented area.
Actinic lichen planus is also known as lichen planus tropicus, lichen planus subtropicus, lichenoid melanodermatitis, lichen planus atrophicus annularis, and summertime actinic lichenoid dermatitis.1 It is a distinct variant of lichen planus that affects mainly children and teenagers.2 The majority of the reported cases are from the Middle East.3 Three clinical types of ALP have been described: annular, dyschromic, and pigmented. The most common form is the annular type, which consists of erythematous brownish plaques with an annular configuration. The dyschromic type presents as discrete and confluent whitish angular papules. Finally, the pigmented type consists of hypermelanotic patches, sometimes assuming a melasmalike appearance.4
Annular Plaque on the Face. Arch Dermatol. 1999;135(12):1543-1548. doi:10-1001/pubs.Arch Dermatol.-ISSN-0003-987x-135-12-dof9025