Maxillary extraskeletal Ewing sarcoma concurrent with non-small cell lung cancer: A case report and review of the literature

Extraskeletal Ewing sarcoma, a high-grade soft tissue tumor, is extremely rare in the stomatognathic region. We report the case of a 47-year-old man with probable extraosseous Ewing sarcoma of the maxillary gingiva that occurred concurrently during chemoradiotherapy for non-small cell lung cancer. Owing to the rapid growth of the mass, debulking surgery was performed for the suspected round cell tumor under intravenous anesthesia. The tumor was considered as having extraosseous Ewing sarcoma showing unusual features based on the following features: it was not continuous with the maxilla; histopathological examination revealed proliferation of small round cells with pleomorphic and voluminous round nuclei in the fibrous connective tissue; tumor cells were immunohistochemically positive for CD99 and ETS-related gene (ERG); and fluorescence in situ hybridization analysis showed EWSR1 gene translocation. Despite satisfactory postoperative recovery, the patient died of respiratory failure due to rapid lung cancer deterioration on postoperative day 16. To our knowledge, in the English literature, there are only 17 reported cases of extraskeletal Ewing sarcoma in the stomatognathic region, and this is the only one with concurrent other organ cancer. More data on cases of extraskeletal Ewing sarcoma in the oral region are needed to establish its pathophysiology, prognosis, and treatment guidelines.