Classification of amyloidosis by laser microdissection and mass spectrometry–based proteomic analysis in clinical biopsy specimens

The clinical management of amyloidosis is based on the treatment of the underlying etiology, and accurate identification of the protein causing the amyloidosis is of paramount importance. Current methods used for typing of amyloidosis such as immunohistochemistry have low specificity and sensitivity. In this study, we report the development of a highly specific and sensitive novel test for the typing of amyloidosis in routine clinical biopsy specimens. Our approach combines specific sampling by laser microdissection (LMD) and analytical power of tandem mass spectrometry (MS)-based proteomic analysis. We studied 50 cases of amyloidosis that were well-characterized by gold standard clinicopathologic criteria (training set) and an independent validation set comprising 41 cases of cardiac amyloidosis. By use of LMD/MS, we identified the amyloid type with 100% specificity and sensitivity in the training set and with 98% in validation set. Use of the LMD/MS method will enhance our ability to type amyloidosis accurately in clinical biopsy specimens.