HYPERTHYROID MYOPATHY WITH MITOCHONDRIAL PARACRYSTALLINE RECTANGULAR INCLUSIONS

The ultrastructural features of a case of severe hyperthyroid myopathy are presented. Along with the moderate increase in mitochondrial size and number usually observed in most patients with hyperthyroid myopat hy, some of the skeletal muscle mitochondria in the present case also contained paracrystalline rectangular inclusions. This finding has not been previously reported in hyperthyroid myopathy and further support s the current view that mitochondrial abnormalities play a major role in the pathogenesis of muscle dysfunction in hyperthyroid patients.