Lichen amyloidosis in a dark skinned patient.

Lichen amyloidosis is a primary localized cutaneous amyloidosis without systemic involvement, characterized by a persistent pruritic eruption of multiple discrete hyperkeratotic papules. The etiology is unknown, but chronic irritation of the skin has been proposed as an etiological factor. We herein report a typical case of lichen amyloidosis in a dark skinned patient. Physical examination revealed slightly shiny, brownish and fine uniform papules approximately 1 cm in diameter, with no accompanying macular lesions. Biopsy specimens taken from some of these papules on the legs showed small globular deposits of an amorphous and slightly eosinophilic substance in the dermis. This substance stained positively with Congo red, indicating the presence of amyloid. In addition, amyloid gave an apple green birefringence when viewed with polarized light.