LICHEN AMYLOIDOSUS - DISEASE ENTITY OR TH E RESULT OF SCRATCHING

In current textbooks of dermatology, lichen amyloidosus is said to be a papular, intensely pruritic type of amyloidosis of unknown aetiology . When this concept was developed, there was no way of discriminating between the different types of amyloid. It is now known that amyloid i n lichen amyloidosus is not derived from immunoglobulins or serum prot eins, as it is in systemic amyloidoses, but from keratin peptides of n ecrotic keratinocytes. Even several years ago, chronic scratching was invoked as a possible cause of damage to keratinocytes in lichen amylo idosus. In support of this hypothesis, four cases are presented. Apart from amyloid in the papillary layer, all biopsy specimens revealed hi stopathological signs of chronic scratching (epithelial hyperplasia wi th hypergranulosis and compact orthokeratosis, coarse collagen in vert ical streaks in the stratum papillare), such as are also found in prur igo nodularis and lichen simplex chronicus. Lichen amyloidosus is cons idered to be a variant of these conditions. Just as in prurigo nodular is and lichen simplex chronicus, pruritus seems to be the cause and no t a symptom of the papular skin lesions. Consequently, treatment of li chen amyloidosus should not be directed at removing amyloid, but at im proving the pruritus.