Pulmonary artery sarcoma with extensive leiomyosarcoma differentiation and heterologous osteosarcomatous elements

•Osteosarcoma differentiation of pulmonary leiomyosarcoma is extremely uncommon.•Cardiac Magnetic Resonance is the most useful tool to diagnose malignant tumors.•The gold standard treatment is complete surgical resection. Pulmonary artery sarcomas are exceptionally unusual. Their clinic, diagnosis and treatment play a very important role in the ultimate outcome and long-term survival. We present the case of a 70-year-old gentleman diagnosed with a leiomyosarcoma of the pulmonary artery with osteosarcoma differentiation that underwent surgical resection and subsequent chemotherapy, with good recovery at 9 months follow-up. Late diagnosis and incomplete surgical resection will worsen the short- and long-term prognosis of these patients.