LICHEN AMYLOIDOSUS - A CONSEQUENCE OF SCRATCHING

Background: Lichen amyloidosus (LA) is generally said to be a pruritic type of amyloidosis of unknown cause. Histopathologically, it is char acterized by epidermal changes of lichen simplex chronicus and by depo sits of amyloid in the papillary dermis that are derived from keratin peptides of necrotic keratinocytes. Chronic scratching is responsible for the development of lichen simplex chronicus and may lead to necros is of individual keratinocytes. Objective: Our purpose was to evaluate whether chronic scratching may also be responsible for the formation of amyloid in LA. Methods: We studied patients with LA in regard to hi stopathologic findings, onset of pruritus, associated diseases, and re sponse to treatment. Results: In most cases, pruritus had preceded the skin lesions. Eight of nine patients suffered from diseases other tha n LA that may be associated with pruritus. Histopathologically, amyloi d was confined to areas that also showed signs of lichen simplex chron icus. Systemic treatment with sedating antihistamines and intense loca l treatment with corticosteroids were found to be effective. Conclusio n: LA is considered to be a variant of lichen simplex chronicus in whi ch scratching leads to necrosis of keratinocytes and eventually to the formation of amyloid in the papillary dermis. Because chronic scratch ing seems to be the cause and not the result of the deposits of amyloi d, treatment should be directed at the amelioration of pruritus.