Isolated Myeloid Sarcoma and Intracardiac Thrombus Resulting in Superior Mediastinal Syndrome.

Superior mediastinal syndrome (SMS) is a relatively common emergency in the practice of Pediatric Oncology. It typically results from the compression of large airways and superior vena cava by a swiftly growing mass. T-lineage acute lymphoblastic leukemia or lymphoma, neuroblastoma, and germ cell tumor are the common etiologies of SMS in children. Occasionally, SMS can be an unexpected presentation of less common childhood cancers and a surprise for the diagnostic and treating teams. The present paper reports the diagnostic and therapeutic challenge of managing a 9-y-old boy with SMS resulting from mediastinal myeloid sarcoma. The presence of a sizeable intracardiac thrombus, in addition, contributed to the SMS. The initial pleural fluid cytology and image-guided fine-needle aspiration cytology of the mediastinal mass were nondiagnostic. A thoracotomy was subsequently performed to debulk the tumor for symptomatic relief and obtain tissue for diagnosis.