[Late myopathy with mitochondrial changes in the muscle].

The ultrastructural finding of abnormal muscle mitochondria has been reported in various conditions, but mostly in association with the clinical picture of ophthalmoplegia, and in cases of "floppy infant" syndrome. In the case herein reported, the mitochondrial abnormalities were found in the muscle biopsy of a 49-year-old man suffering from a late onset proximal myopathy; he was affected also by polyneuropathy, subclinical thyroid dysfunction, disturbances of heart conduction, and unilateral gynaecomastia. The association of abnormal muscle mitochondria and late onset myopathy without involvement of the extraocular muscles has been reported in a very few cases. It is not possible, at present, to state that these cases represent a nosological entity; the existence of an underlying biochemical defect, accounting for the mitochondrial abnormalities, could be suspected, but it seems more probable that these changes are non-specific features of muscular damage, possibly related to the stage and the degree of the process. In this view, the coexistence of neurogenic damage, gastrointestinal malabsorption, and thyroid dysfunction, could play an additional role in the case herein described. Finally, the coexisting findings of cardiac, endocrine, and neuropathic damage are discussed with regard to the Kearns-Sayre syndrome, which also associates mitochondrial myopathy and multisystemic involvement.