Diagnosis and immunohistochemical classification of systemic amyloidoses. Report of 43 cases in an unselected autopsy series.

Fourty-three cases of systemic amyloidosis were identified in an unselected autopsy series from our institute (6305 autopsies between 1979 and 1993) and classified immunohistochemically by means of a panel of antisera directed against five major amyloid fibril proteins. Amyloid A (AA) amyloidosis was the most common type, being found in 21 cases (48.8%). Transthyretin-derived (ATTR) amyloidosis was present in 11 cases (25.6%), and immunoglobulin light chain-derived (AL) amyloidosis in 10 cases (23.3%). A single case (2.3%) contained deposits of more than one type of systemic amyloid. AA amyloidosis was associated with chronic inflammatory or infectious diseases (81%), malignant tumours (19%) or both (9.5%). Immunoglobulin light chain-derived amyloidoses were associated with myeloma (50%) or primary (idiopathic; 50%). In AA and AL amyloidosis the kidney was the organ most frequently involved. ATTR amyloid affecting mostly the heart and lungs presented as senile systemic amyloidosis. Systemic amyloidosis was the cause of death in 5 cases (12%) and caused symptoms in 17 cases (39%). Our results suggest that most cases can be classified by using a panel of sensitive and specific antibodies against five major amyloid fibril proteins. This technique may make amyloid type-specific therapy possible for AL amyloid patients who do not have evidence of an underlying plasma cell dyscrasia.