Acute pulmonary thromboembolism associated with interstitial pneumonia.

A 68-year-old woman, who had been diagnosed as idiopathic interstitial pneumonia, complained of progressive dyspnea on exertion for a week. Although her chest radiograph did not worsen, arterial blood gas findings were markedly worsened. Contrast-enhanced chest computed tomography showed filling defects of the right upper and middle lobe branches of the pulmonary artery. She was diagnosed as having acute pulmonary thromboembolism (APTE). Clinical symptoms and contrast-enhanced chest computed tomography findings were remarkably improved after the treatment with heparin and urokinase. APTE should be considered as a differential diagnosis in patients with interstitial pneumonia who have worsening of respiratory symptoms with unchanged chest radiograph.