[Massive pulmonary thromboembolism found at autopsy in a patient with a 14-year history of polymyositis-associated nonspecific interstitial pneumonia].

: A 64-year-old woman with a 14-year history of refractory nonspecific interstitial pneumonia (NSIP) associated with polymyositis was admitted urgently to our hospital due to acute exacerbation of dyspnea. The first episode of dyspnea had occurred 14 years earlier and the diagnosis of cellular and fibrotic NSIP had been made by radiographic examinations and open lung biopsy. Her NSIP initially responded well to high-dose prednisolone therapy (40mg/day), but flared when the dose of prednisolone was tapered. Three years after the diagnosis of NSIP, a diagnosis of polymyositis was made based on her elevated serum level of creatinine phosphokinase and muscle biopsy findings. Her polymyositis was controlled well by prednisolone therapy, but her NSIP gradually worsened, despite treatment with several courses of methylprednisolone pulse therapy and immunosuppressive agents. She was brought to our hospital by ambulance due to acute progression of dyspnea and was admitted. Chest X-ray film revealed diffuse interstitial shadows and marked enlargement of the right atrium and bilateral pulmonary arteries. Transthoracic echocardiogram revealed severe dilatation of the right atrium and right ventricle with an estimated pulmonary artery systolic pressure of 84mmHg. She died of progressive respiratory failure on day 4 of hospitalization. Autopsy revealed massive thrombi that completely obstructed the bilateral pulmonary trunks. Histological examination revealed that these thrombi were organized, and her interstitial lung disease (ILD) was specified as fibrotic NSIP with microscopic honeycomb. Massive pulmonary thromboembolism is extremely rare in patients with polymyositis-associated NSIP, but it should be considered as a possible cause of acute exacerbation of respiratory failure. This case provides valuable information on the clinical and pathological course of polymyositis-associated NSIP.