Pulmonary artery sarcoma (PAS) is a rare and highly malignant tumor of pulmonary artery origin. Since 1923, when the first case was reported, <300 cases have been reported worldwide. PAS has a poor prognosis, and early diagnosis with radical surgical resection offers patients with PAS the only chance of survival. However, due to its rarity and the non-specificity of its clinical manifestations and imaging presentation, PAS is frequently misdiagnosed as a pulmonary thromboembolic disease, including pulmonary thromboembolism (PTE) and chronic thromboembolic pulmonary hypertension (CTEPH). The present study reports three cases of PAS that were initially misdiagnosed as PTE or CTEPH, and were later shown to be PAS following surgery. In addition, the clinical features of these patients are examined in order to improve the differential diagnosis of PAS during the early stages of the disease, when the prognosis of patients with PAS is at its optimum.