Pulmonary artery sarcoma is highly malignant and easily metastasizes to the systemic organs. Both the introduction of novel diagnostic procedures and the development of new treatment modalities are required to achieve long-term survival. Several studies have shown that platelet-derived growth factor receptor α (PDGFRα) gene amplification is frequently observed in pulmonary artery sarcoma. PDGFRα is known to be involved in cell proliferation in certain malignancies. PDGFRα may become a potential biological marker in pulmonary artery sarcoma. We report a case in which a diagnosis of pulmonary artery sarcoma overexpressing PDGFRα was made using endovascular catheter biopsy following positron emission tomography with integrated computed tomography (PET/CT) scans.