Immunoglobulin light-chain (AL) amyloidosis with myasthenic symptoms and echocardiographic features of dilated cardiomyopathy.

Myasthenic symptoms and the echocardiographic findings of dilated cardiomyopathy are very rare in primary AL amyloidosis. We report a 59-year-old man with dyspnea on effort and weakness after exercise. His electrocardiogram showed ischemic heart disease and echocardiography indicated dilated cardiomyopathy. Muscle biopsy revealed amyloidosis with deposits of lambda light chain-derived amyloid within the vessel wall. Treatment with PGE1 resulted in improvement of the myasthenic symptoms. This patient indicates that myasthenic symptoms and dilated cardiomyopathy would be a unique syndrome associated with systemic AL amyloidosis involving mainly the small vessels, i.e., AL amyloid angiopathy, in the skeletal muscles and myocardium vessels.