Answer is C (Testicular involvement) Testicular involvement / enlargement is a typical poor prognostic factor for childhood ALL Age < 2 years versus Testicular Involvement Typically Age < 1 year is considered a poor prognostic factor Although Age < 2 year has been mentioned as a poor prognostic factor in ceain textbooks including Hoffman's Hematology (4th/1158) most textbooks use the criteria of Age < 1 year to define a poor prognostic factor Since testicular involvement provided amongst the option is an established poor prognostic factor, this is selected as the single best answer of choice.