Contrast enhance CT has been done shown below  reveals huge moderately enhancing anterior mediastinal mass .

CT guided biopsy of mass is done histopathological reports shows Biphenotypic Leukemia.

Treatment is given in the form chemotherapy ,on follow up X ray mass has reduced to almost negligible size. Only abnormality seen in last X ray is small patch of left paracardiac consolidation. Child is also improved symptomatically.