Immunochemical microanalysis of amyloid proteins in fine-needle aspirates of abdominal fat

Diagnosis of systemic amyloidosis by fine-needle aspiration biopsy of abdom inal fat is well established. A complete diagnosis now must include determi nation of the chemical type of amyloid. Microextracts of amyloid proteins f rom 11 Congo red-positive aspirate samples were analyzed with immunochemica l methods. There was correspondence of the results obtained by immunohistol ogic and Western blotting analyses in 3 of 4 specimens with kappa light cha in amyloid, 5 of 6 with lambda amyloid, and 1 with amyloid A. The method pr ovides rapid and reliable diagnostic information necessary for classificati on of the chemical type of amyloid required for initiation of specific mode s of therapy, with little discomfort to the patient.