Breast cancer shortly after the diagnosis of interstitial pneumonia associated with polymyositis.

Polymyositis is sometimes associated with pulmonary fibrosis or malignant diseases, however, rarely with both simultaneously. For such patients, no criterion for initial treatment and tapering of steroid has been reported. We describe a patient who had breast cancer and interstitial pneumonia associated with polymyositis. In this case, slow tapering of the steroid was an important aspect of the treatment, and close clinical follow-up was necessary to monitor for disease exacerbation.