[Secondary pulmonary hypertension due to pulmonary tumor thrombotic microangiopathy diagnosed by open lung biopsy].

A 67-year-old woman was admitted with progressive exertional dyspnea. Arterial blood gas analysis showed severe hypoxia. A chest radiograph and a computed tomography showed bilateral interstitial infiltrations and patchy ground-grass opacities. Initially, she was given antibiotics with no effect. Since transthoracic echocardiography revealed right ventricular overload, cardiac catheterization was performed, which showed pulmonary hypertension. Pulmonary angiography revealed irregular filling defects along with pulmonary peripheral sites. Open lung biopsy was performed to establish a definitive diagnosis and to treat the diffuse lung disease. Microscopically, multiple tumor thrombi of mucinous adenocarcinoma were found in small sized pulmonary artery. Primary sites of malignancy has not been found in spite of postoperative examinations.