Primary mediastinum Ewing's sarcoma with pleural effusion: A case report and literature review

Ewing's sarcoma (ES) is an aggressive cancer in young adults. Primary ES occurring in the chest with pleural effusion is even rarer. We report the case of a 15-year-old girl who presented with intermittent chest pain occurring for more than 2 months and cough and wheezing for 10 days. Radiological imaging showed a large soft tissue mass with multiple small vessel shadows near the left med-iastinum and bloody pleural effusion in the left thorax. ES was diagnosed by positive immunostaining for CD99, FLI-1, and NKX2 combined with fluorescence in situ hybridiza-tion detection of the EWSR1 gene arrangement. With che-motherapy, lung computed tomography revealed that the tumor had become much smaller, and the fluid was absorbed. We reporta case of extraskeletal Ewing's sarcoma (EES) in the mediastinum with pleural effusion, which is unusual and chal-lenging. EES is a highly malignant tumor with a poor prog-nosis. Early diagnosis and treatment can improve the survival rate of patients.