NEONATAL MIXED LINEAGE ACUTE-LEUKEMIA

We report here an uncommon case of neonatal acute leukaemia that prese nted concomitant with serological evidence of rubella infection. The c linical course was aggressive and the patient died 5 days after diagno sis from septicaemia. Leukaemic blasts had a mixed lineage immunopheno type co-expressing a constellation of B-lymphoid (CD19, cytCD22, TdT) and myeloid (CD13, CD33, CD14, anti-MPO) markers, as well as multiple adhesion molecules and markers associated with early lympho-myeloid pr ogenitor cells (CD34, CD7, HLA-DR). A previously unrecorded discordant expression of different CD10 and CD34 epitopes was identified using d ifferent monoclonal antibodies. The karyotype was 46,XX t(4;11)(q21;q2 3) and molecular analysis confirmed rearrangement of the trithorax-rel ated oncogene HRX at 11q23. There was a clonal biallelic rearrangement of the immunoglobulin heavy-chain gene. The features of this rare cas e have implications for possible aetiological events leading to leukae mia.