Commonest site of extramedullary relapse of ALL
Despite success of modern treatment,20-30% of children with ALL relapse.The main cause of treatment failure in leukemia is relapse of the disease.Common sites of relapse are the bone marrow(20%),central nervous system(5%),and testis(3%).Relapse in extramedullary sites,paicularly testes,is more ourable in terms of survival. Reference:Essential pediatrics-Ghai,8th edition,page no:604
CNS
Lung
Liver
Testis
Childhood tumors