Pulmonary artery leiomyosarcoma is an extremely rare disease, with only a few dozen cases reported worldwide to date. This disease is easily misdiagnosed as pulmonary thromboembolism, leading to improper treatment and accurate diagnosis in the later stages of the disease. Furthermore, this delayed diagnosis may also be the reason for the extremely high mortality rate of patients suffering from it. Early invasive surgery with the goal of complete surgical resection is the standard treatment method. Chemotherapy and radiation therapy have been tried with variable outcomes.