Resecting a giant malignant lung tumor in a patient with unilateral acute interstitial pneumonitis.

Acute interstitial pneumonia is a rare and fulminant form of idiopathic interstitial lung disease. Here, we report a case of a giant malignant sarcomatoid tumor of the left lung with unilateral lung infiltration. The tumor was resected under venovenous extracorporeal membrane oxygenation support. Right middle lung lobe biopsy revealed alveolar epithelial hyperplasia, mild interstitial fibrosis, and interstitial edema. The patient was diagnosed with acute interstitial pneumonitis, and effectively treated with steroid pulse therapy followed by prednisolone. In this case, the contralateral lung expansion accomplished with tumor resection, definitive diagnosis based on lung biopsy, and corticosteroid treatment possibly improved the outcome.