IMMUNOHISTOLOGIC CLASSIFICATION OF SYSTEMIC AMYLOIDOSIS BY FAT ASPIRATION BIOPSY

Amyloidosis in the modern era is a spectrum of disease caused by an ev er-increasing number of chemically different fibrillar proteins that a ccumulate in tissues. The different amyloid types can be distinguished by immunohistochemical examination of involved tissues. We describe t he use of immunofluorescence and immunoelectron microscopy to determin e the chemical type of amyloid in 16 fat aspirates from 16 patients wi th amyloid deposits in their abdominal fat. The amyloid in 12 specimen s was classified as lambda light chain type and in 3 as kappa light ch ain. Only one aspirate could nor be immunohistochemically classified. Corroborative data included a corresponding monoclonal lg in the serum or urine in 15 of 16 patients, a corresponding restricted clonality o f bone marrow cells in 10 of 11 patients, and the detection of the sam e light chain isotype in other tissues with amyloid in 8 of the patien ts, Fat aspiration biopsy is a rapid, safe and cost-effective method f or diagnosis and classification of the chemical type of amyloid.