A monoclonal anti-keratin antibody reactive with amyloid deposit of primary cutaneous amyloidosis

Specimens from cutaneous amyloidoses (lichen amyloidosis and macular amyloidosis) were stained immunohistochemically with monoclonal anti-keratin antibodies. One monoclonal antibody raised against hair keratin (HKN-6) reacted with the amyloids of both primary amyloidoses. Another monoclonal antibody, HKN-2, did not decorate the amyloid deposit. HKN-6 did not stain the interfollicular epidermis, but HKN-2 did. The possible explanations of these findings are 1) amyloid deposits contain keratin protein modulated to react with HKN-6; 2) amyloid deposits contain a protein unrelated to keratin protein, but reactive to HKN-6.