This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
All of the following are poor prognostic factors in a case of acute myeloid leukemias, except: 
Select and explain. 
A. Age more than 60 years, B. Presence of t(8:21), C. Secondary leukemias, D. Leucocyte count more than 1,00,000/microl
B: Presence of t(8:21)
Answer: B: Presence of t(8:21) 
Explanation: Patients t(8;21) and inv(16) has a good prognosis, approximately 55% of these patients are cured. t(15:17) is associated with a very good prognosis, while those without any cytogenetic abnormality have a moderately orable outcome. Ref: Harrison's Internal Medicine, 18th Edition, Chapter 109