leukaemia cancer symptomslymphocytic leukaemia symptomssigns of childhood leukaemialymphoblastic leukaemia symptomschronic leukaemia symptomssymptoms of leukaemia in teenagermyeloid leukaemia symptomsleukaemia nosebleedssymptoms of leukaemia in elderlyleukaemia petechiaeacute leukaemia symptomsleukaemia bruising