Amyloid deposits in lymph nodes. A morphologic and immunohistochemical study

In a series of approximately 80,000 lymph nodes, amyloid deposition was found in 18; 12 of those nodes were selected, on the basis of availability of specimens, for investigation by immuno-histochemical typing to identify the protein of origin and by correlation with morphologic criteria and clinical information. Four patterns of amyloid deposition were identified: lymph node vessel involvement, follicular deposition, diffuse deposition, and a combination of follicular and diffuse deposition. All cases were classified immunohistochemically with the amyloid type-specific antisera anti-AA, anti-A λ, anti-A κ, anti-ASc₁, and anti-AF. Immunoglobulin-derived protein (AL) in lymph nodes was found in every case of isolated amyloidosis, lymphoplasmacytic/lymphoplasmacytoid immunocytoma, plasmacytoma, and idiopathic amyloidosis. Among the cases of AL amyloidosis were nine of A λ and one of the A κ type. AA protein was present in two cases of reactive systemic amyloidosis. There was no useful morphologic correlation with the immunohistochemically identified amyloid types.