Severe mitochondrial cardiomyopathy and extra-neuromuscular abnormalities in mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episode (MELAS).

An autopsy case of mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS) in a 56 yr-old woman is reported. Histopathologic abnormalities are shown widely in the heart, liver, kidney, pancreas and thyroid gland, other than the central nervous system and skeletal muscles that had been so far emphasized in the cases of MELAS. Particularly in the myocardium, focal fibrosis and a disarray of myofibrils were demonstrated, which closely resembled that seen in idiopathic hypertrophic cardiomyopathy. In addition, unique mitochondrial abnormality exhibiting a central glycogen aggregation with surrounding multiple radiating cristae was noted in some cardiomyocytes, which has never been reported in previous cases of MELAS. Thus, in MELAS, various histopathological abnormalities including the mitochondrial abnormalities may involve tissues other than those of the neuromuscular system.