[A case of chronic progressive external ophthalmoplegia presenting as inflammatory myopathy]

A 64-year-old female had slowly progressive bilateral external ophthalmoplegia, blepharoptosis and muscle weakness of the extremities since age 30. Laboratory examination showed an elevation of serum CK level. Biopsied specimens from the left biceps and the left orbicularis oculi muscles revealed myopathic change with infiltration of mononuclear cells. In addition, some ragged-red fibers and a few cytochrome c oxidase-negative fibers, which are characteristic of mitochondrial myopathy, were observed. Polymerase chain reaction analysis of mtDNA in the muscles showed multiple mtDNA deletions. On administration of prednisolone (initial dose, 60 mg/day), blepharoptosis and muscular strength improved transiently and serum CK level was normalized but external ophthalmoplegia was not improved. We diagnosed our case as chronic progressive external ophthalmoplegia (CPEO). This is the first report of CPEO presenting as inflammatory myopathy.