A mediastinal mass mimicking asthma symptoms.

Extramedullary myeloid sarcoma is a rare form of myelogenous leukemia. It can involve any anatomical body part. Mediastinal involvement is reported in only few cases. We report on a case of extramedullary myeloid sarcoma presenting as a mediastinal mass in a previously healthy nonleukemic male teenager with primary asthmatic complaints and the signs of superior vena cava syndrome.