We present two cases of
interstitial pneumonia with anti-Jo-1
antibodies in the absence of
myositis. The first patient was a 38-year-old woman and the second, a 59-year-old woman. Both patients were admitted to our hospital complaining of dry
cough and
dyspnea on effort. The diagnosis of
interstitial pneumonia was made from chest radiography, computed tomography and surgical lung biopsy. Anti-Jo-1
antibodies, which were highly specific for
polymyositis and
dermatomyositis (PM/DM), were detected in both patients. However, the serum
creatine kinase concentrations and electromyographic findings in both patients were normal, and no clinical signs (including
muscle weakness,
rash and
arthralgia) were found. In the first patient, oral
prednisolone (PSL) treatment (20 mg day) improved the
interstitial pneumonia, but PSL has now been tapered to 17.5 mg day. In the second patient, oral PSL treatment (40 mg day) improved
interstitial pneumonia, and the dose was tapered to 5 mg day. The second patient was followed for more than 10 years
after treatment, but she has never shown any signs of clinical
myositis. Further investigation will be required, because no pathophysiological relation between anti-Jo-1
antibodies and
interstitial pneumonia with PM DM has yet been established.