Primary Extraosseous Ewing's Sarcoma of the Lung: Radiologic and Pathologic correlation

Ewing's sarcoma (ES) is a rare and highly aggressive tumor belonging to a family of neoplasms of neuroectodermal origin, which primarily affects the bones or soft tissues. ES originating from lung parenchyma without chest wall involvement is extremely rare with less than 40 cases reported in the English literature. A 41-year-old man admitted to the thoracic surgery department presenting with intermittent non-productive cough, dyspnea, left-sided chest pain for two months for further evaluation and treatment with a preliminary diagnosis of pulmonary mass. Contrast-enhanced thorax CT and MRI revealed a large heterogeneous soft-tissue mass in the left lower lobe with no distant metastases or occult primary tumor. Following the percutaneous transthoracic biopsy, histopathological and immunohistochemical results were consistent with primary pulmonary ES. Though rare, primary pulmonary ES should be considered in the differential diagnosis of young patients presenting with a large heterogeneous soft tissue mass in the lung. This case report highlights the diagnosis, radiologic and pathologic findings, and management of primary pulmonary ES.