This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Childhood tumors, Subject name: Pediatrics
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 ? 
Select and explain. 
A. Presence of mediastinal mass, B. Age between 1 and 10 years, C. Hyperploidy with more than 50 chromosomes, D. WBC count less than 50,000\/mm3 at diagnosis
A: Presence of mediastinal mass
Answer: A: Presence of mediastinal mass 
Explanation: 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.