Fatal respiratory failure due to polymyositis.

A patient presenting as severe respiratory failure due to alveolar hypoventilation resulting from respiratory muscle weakness is described. Diagnosis of polymyositis was established by electromyography and muscle biopsy. Steroid therapy was initiated and it ameliorated respiratory failure remarkably. Selective respiratory muscle involvement due to polymyositis has been suggested in this patient. Although fatal respiratory failure is a very rare complication in polymyositis, polymyositis should be considered as one of underlying diseases causing severe respiratory failure.