Pulmonary artery sarcoma presenting as an isolated lung mass

We report a very rare case of pulmonary artery sarcoma that presented as an isolated lung mass, which we attempted to resect via lobectomy, although this resulted in incomplete resection due to unnoticed latent proximal presentations. A 54-year-old man complained of a dry cough that had persisted for 2 months. Enhanced chest computed tomography revealed a lobular mass in his left lower lobe. Therefore, left lower lobectomy was performed as a radical surgery, and the tumor was ultimately diagnosed as pulmonary artery sarcoma. However, follow-up computed tomography at 16 months revealed proximal presentations in the pulmonary trunk and right pulmonary artery, which we retrospectively discovered were present before the surgery. This case highlights the importance of evaluating the lumen of the pulmonary artery, to accurately determine the required extent of any radical surgery, even in cases of pulmonary artery sarcoma that presents as an isolated lung mass.