Pt probably presented already in sepsis (overwhelming blood infection) from his defeated immune system. Probably had renal failure also. They only discovered the leukemia as part of the work up of his symptoms at the hospital. Not all that uncommon actually.
An analogy would be like saying a person died withing 24 hours of being diagnoses with atrial fibrillation. Well, actually, they died of the stroke which was caused from the atrial fibrillation that was diagnosed after the stroke happened.
can the fatal effects of leukemia progress more rapidly than all the other symptoms and routine checkups that normally provide a clue about such an illness?