Introduction
Transient abnormal myelopoiesis (TAM) is a pre-leukaemic, often self-limiting, condition seen in neonates with trisomy 21 (Down syndrome (DS)). While many cases spontaneously resolve, in up to a quarter of patients it is a herald for later development of myeloid leukaemia of DS (MLDS).1 Acquired somatic mutations in exon 2 of the haematopoietic transcription factor gene GATA1 are diagnostic of the condition and the oncogenic link between these related disorders. GATA-1 mutations can be identified in all cases of TAM and MLDS.2 TAM itself carriers a 20% mortality risk and, in the presence of life-threatening signs such as organomegaly causing respiratory distress, white cell count (WCC) >100, or pleural or pericardial effusions, therapeutic intervention is indicated.3 In the majority of such cases, a short, single cycle of low intensity chemotherapy, such as low dose cytarabine (LDAC) is effective in controlling disease.1
We present an extremely recalcitrant case of a TAM in whom disease control was only achieved following four courses (24 doses) of LDAC. WCC reduction and clinical stabilisation was achieved without need to escalate to more intensive MLDS treatment and was well tolerated. No reported cases of TAM have required so many doses of LDAC, with a recent study of 167 cases reporting a maximum of twelve doses.1