Actinic lichen planus (ALP) is a form of lichen planus associated with sun exposure.
Features of actinic lichen planus:
(1) The lesions occur in sun-exposed skin of patients with dark skin.
(2) A lesion shows a reticulated white plaque with or without vesicles.
(3) Lesions on sun-exposed sites may be present with lesions elsewhere, or it may be limited to a single site such as the lower lip. The patient may or may not have a history of lichen planus.
(4) A biopsy of the lesion shows:
(4a) thinning of the epithelium with subepidermal clefting
(4b) interface vacuolar change
(4c) dermal band of lymphocytes, plasma cells and histiocytes
(4d) negative stains for micro-organisms
(4e) negative direct immunofluorescence
(5) Other causes of lichenoid lesions (drug eruptions, autoimmune blistering disease, Herpes simplex, etc) are excluded.
