Step-by-step typing for the accurate diagnosis of concurrent light chain and transthyretin cardiac amyloidosis

While ^99mTc-pyrophosphate scintigraphy is clearly useful in diagnosing transthyretin amyloid cardiomyopathy (ATTR-CM), it is necessary to know the pitfalls of this test for proper use. We present a rare case of concurrent ATTR-CM and amyloid light chain (AL) cardiomyopathy. The patient showed congestive heart failure with left ventricular hypertrophy. ^99mTc-pyrophosphate scintigraphy revealed abnormal cardiac uptake of Grade 3, a typical feature for ATTR-CM. However, the patient showed renal impairment with proteinuria and the presence of monoclonal gammopathy, which rather suggested AL amyloidosis. Endomyocardial biopsy, immunohistochemistry, and proteomic analysis by laser microdissection with liquid chromatography-coupled tandem mass spectrometry were performed, which finally confirmed both ATTR-CM and AL cardiomyopathy. This case implicates the importance of combining examinations and precisely interpreting the results to diagnose cardiac amyloidosis accurately.