[A case with polymyositis associated with primary hyperparathyroidism].

A 67-year-old woman was admitted to our department because of 5 years' duration of proximal muscle weakness. Serum CK was high, and EMG showed myogenic pattern, and muscle biopsy revealed remarkable inflammatory cells infiltrating around the destroyed muscle fibers. Her muscle weakness and hyperCKemia markedly improved by corticosteroid therapy, suggesting that the diagnosis was compatible with polymyositis (PM). In addition, serum calcium was high and phosphate was low. Serum parathormone level significantly elevated. The findings of diagnostic imaging procedures including echography, scintigraphy, and computed tomography of the parathyroid glands suggested presence of parathyroid adenoma with cystic degeneration in the thyroid tissue. There was only one case report of PM associated with primary hyperparathyroidism (PHP) as the literature referred. In this case, we could not prove direct relationship between PM and PHP. The association might have been coincidental. However, PHP might have played some role in the pathogenesis of muscular involvement, or there might be a similar immunological mechanism as seen between PM and malignancy. It is possible that association of PM and PHP is more frequent than generally considered. It may be necessary to pay more attention to find out the association of PM and PHP.