leukaemia cancer symptomslymphocytic leukaemia symptomssigns of childhood leukaemialymphoblastic leukaemia symptomssymptoms of leukaemia in teenagerleukaemia relapse symptomsmyeloid leukaemia symptomsleukaemia nosebleedssymptoms of leukaemia in elderlyleukaemia petechiaeacute leukaemia symptomsleukaemia bruising