[Progressive respiratory failure and weakness in a 61-year-old woman].

A 61-year-old woman was admitted with a suspected diagnosis of atypical pneumonia. Extended diagnostic measures revealed interstitial lung disease (ILD), polyserositis, polyarthritis and myopathy. With detection of an antibody against PL-7 (anti-threonyl-transfer-RNA synthetase) the diagnosis of anti-synthetase syndrome (ASS) was established. ASS are rare inflammatory myopathies which frequently present as multisystemic diseases with severe organ involvement. An immunosuppressive regimen with steroids and cyclophosphamide led to successful induction of disease remission. Maintenance therapy will be conducted with azathioprine. ASS should always be considered in the differential diagnosis of myopathies and ILDs.