A family of a child just diagnosed wit acute lymphoblastic leukemia asks about the child's prognosis. Which of the following is a poor prognostic indicator ?

Presence of a large mediastinal mass can lead to tracheal compression,producing tachypnoea & respiratory distress(superior mediastinal syndrome).A large mediastinal mass may sometimes cause superior vena cava syndrome with facial edema and plethora,throbbing headache,conjunctival congestion,and dilated neck veins.So mediastinal mass is a poor prognostic factor. The presence of hyperploidy(chromosome number >50,DNA index>1.16) is associated with good prognosis.Other good prognostic factors are : total WBC count <50,000/mm3 and age between 1-10 years. Reference:Essential pediatrics-Ghai,8th edition,page no:600,601.