Pulmonary artery aneurysms due to Behcet's disease are mainly seen in young males and very rarely in females. To our knowledge there are only 10 cases reported in the related literature. Emergent transcatheter embolization was performed in a female patient with a known history of Behcet's disease in whom massive hemoptysis developed because of rupture of a giant pulmonary artery aneurysm. At 6-month follow-up, transformation of the aneurysm sac into an air cavity was detected. To our knowledge, such a transformation has never been reported in the literature before. Embolization of the pulmonary artery aneurysm and the mechanism of cavity transformation are reviewed and discussed.