Primary leiomyosarcomas of the lung are tumors. We report a case of 49-year old female with history of cough, breathless at rest, right sided chest pain. Chest CT showed a huge (16 cm) mediastinal mass located on the right mediastinum encasing the right main pulmonary artery and infiltrating the main right bronchus and pericardium. The tumor was resected with combined pericardiectomy and pnemonectomy via hemiclamshell incision. This surgical access provided an adequate exposure of the chest "blind zones" and it allowed a radical and safe surgical resection of lung, pleura, pericardium and diaphragm. The final diagnosis showed a low grade differentiation leiomyosarcoma.