Demonstration of amyloid A (AA) protein and amyloid P component (AP) in deposits of systemic amyloidosis associated with renal adenocarcinoma.

The fibril protein in three cases of systemic amyloidosis associated with renal adenocarcinoma was identified as amyloid A protein (AA) using immunohistochemical staining techniques. Amyloid P component was also present in all deposits. In one case unfixed snap frozen tissues were studied directly whilst in the other two, which were investigated retrospectively, fixed paraffin sections were stained by immunofluorescence and immunoperoxidase methods after treatment with trypsin. Enzymatic digestion was necessary to restore reactivity with anti-AP but anti-AA reacted well without any such treatment. These findings establish that renal carcinoma, the carcinoma most frequently associated with systemic amyloidosis, causes the same type of secondary or reactive systemic amyloid as chronic infections and inflammatory disorders.