Paediatric ambiguous lineage leukaemia with monocytic differentiation at diagnosis: case series and review of literature

Ambiguous lineage leukaemia (ALAL) is a rare sub-type of paediatric acute leukaemia. There are four main subgroups according to the lineage of differentiation, namely: (i) mixed phenotype acute leukaemia (MPAL), (ii) bilineal acute leukaemia, (iii) undifferentiated acute leukaemia, and (iv) acute leukaemia with early switch to a different lineage.1-4 MPAL accounts for 1–2% of paediatric leukaemia.3 The World Health Organization (WHO) classifications (2008 and 2016) have established strict criteria for diagnosis of MPAL, emphasising myeloperoxidase for myeloid lineage, cytoplasmic cluster of differentiation 3 (CD3) for T lineage, and CD19 and other B markers for B lineage.1,