NK-lymphoblastic leukaemia/lymphoma, considered a provisional entity in WHO-HAEM4R, is not separately listed in WHO-HAEM5 because of lack of clear-cut and reliable diagnostic criteria, lack of published information on expression on NK-cell-associated antigens such as CD94 and CD161, and marked morphologic and immunophenotypic overlap with other entities, such as blastic plasmacytoid dendritic cell neoplasm, CD56+ T-ALL, CD56+ acute myeloid leukaemia and CD56+ acute undifferentiated leukaemia [209]. Here, NCAM1 is linked to acute lymphoblastic leukemia.