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Against a background of ever increasing expenditure on blood safety, less attention has been paid to improving the safety of the transfusion chain within hospitals. Based on reports to the Serious Hazards of Transfusion (SHOT scheme) between 1996 and 2003, the risk of an error occurring during transfusion of a blood component is estimated at 1:16 500, an ABO incompatible transfusion at 1:100 000 and the risk of death as a result of an 'incorrect blood component transfused' (IBCT) is around 1:1 500 000. There are opportunities for error at a number of critical points in the transfusion chain, starting with the decision to transfuse, prescription and request, patient sampling, pretransfusion testing and finally the collection of the component from the blood refrigerator and administration to the patient, consistently the commonest error in successive SHOT reports. Successive 'Better Blood Transfusion' initiatives and the 2003 Annual Report of the Chief Medical Officer for England have drawn welcome attention to the importance of safe and appropriate transfusion and the National Patient Safety Agency has now set a target of reducing the number of ABO incompatible transfusions by 50% over 3-5 years.

This study of children and adults with acute lymphoblastic leukaemia (ALL) is the largest series of patients with hypodiploidy (<46 chromosomes) yet reported. The incidence of 5% was independent of age. Patients were subdivided by the number of chromosomes; near-haploidy (23-29 chromosomes), low hypodiploidy (33-39 chromosomes) and high hypodiploidy (42-45 chromosomes). The near-haploid and low hypodiploid groups were characterized by their chromosomal gains and a doubled hyperdiploid population. Structural abnormalities were more frequent in the low hypodiploid group. Near-haploidy was restricted to children of median age 7 years (range 2-15) whereas low hypodiploidy occurred in an older group of median age 15 years (range 9-54). Patients with 42-45 chromosomes were characterized by complex karyotypes involving chromosomes 7, 9 and 12. The features shared by the few patients with 42-44 chromosomes and the large number with 45 justified their inclusion in the same group. Survival analysis showed a poor outcome for the near-haploid and low hypodiploid groups compared to those with 42-45 chromosomes. Thus cytogenetics, or at least a clear definition of the modal chromosome number, is essential at diagnosis in order to stratify patients with hypodiploidy into the appropriate risk group for treatment.

Concern about late adverse effects of cranial radiotherapy (XRT) has led to alternative approaches to eliminate leukaemia from the central nervous system (CNS) in childhood acute lymphoblastic leukaemia (ALL). The Medical Research Council UKALL XI trial recruited 2090 children with ALL between 1990 and 1997. Median follow-up is 7 years 9 months; event-free survival (EFS) and overall survival were 63.1% and 84.6%, respectively, at 5 years and 59.8% and 79.4% at 10 years. The isolated CNS relapse rate was 7.0% at 10 years. Patients were randomized for CNS-directed therapy within white blood cell (WBC) groups. For WBC <50 x 10(9)/l, high-dose intravenous methotrexate (HDMTX) (6-8 g/m2) with intrathecal methotrexate (ITMTX) was compared with ITMTX alone, and was significantly better at preventing isolated and combined CNS relapse, but non-CNS relapses were similar. There was no significant difference in EFS at 10 years, 64.1% [95% confidence interval (CI) 60.4-67.8] with HDMTX plus ITMTX, and 63.0% (95% CI 59.5-66.5) with ITMTX alone. For WBC >/=50 x 10(9)/l, HDMTX with ITMTX was compared with XRT and a short course of ITMTX. CNS relapses were significantly fewer with XRT, but there was a non-significant increase in non-CNS relapses. EFS was not significantly different, being 55.2% (95% CI 47.8-62.6) at 10 years with XRT and 52.1% (95% CI 44.8-59.4) with HDMTX plus ITMTX.

The case records of 99 consecutive children with acute lymphoblastic leukaemia who received either 6-thioguanine (6-TG) or 6-mercaptopurine (6-MP) as maintenance therapy for at least 1 year were reviewed for hepatic veno-occlusive disease (VOD). Overall, 12% of those on 6-TG developed VOD (all boys). Isolated persistent thrombocytopenia appeared to be the earliest indicator of incipient VOD. Multivariate analysis identified male sex and 6-TG as risk factors. In all cases, VOD was mild and reversible on withdrawing 6-TG or replacing it with 6-MP. The data implicate a sex-linked polymorphic variation in xenobiotic pathways of thiopurine metabolism in the pathogenesis of VOD.

Children who have completed treatment for acute lymphoblastic leukaemia (ALL) are commonly followed up for the first 5 years with regular full blood counts (FBCs) to monitor for relapse of disease. There is little evidence to suggest that this practice improves the detection rate of unexpected relapse. Surveillance FBCs, performed on 43 children with relapsed ALL between 1990 and 1999, were analysed. Of the 42 relapses in children off therapy, only two were detected by an abnormal FBC. Routine FBCs in asymptomatic children off therapy lacks specificity in detecting unexpected relapses and maybe safely discontinued.

Consecutive children suffering from pre-B lymphoblastic leukaemia (pre-B ALL) were compared with those who had 'common' ALL (C-ALL) to assess any clinical and pathological differences between the two groups. Over 101 months 27 pre-B children were seen-an incidence in the population served of around 0.8/100,000 per year. There was some time-clustering and 12 of the 27 presented in one year (1987). The 51 patients with C-ALL who presented for comparison were distributed more evenly over the study period. Pre-B children had more basophilic blast cells with less periodic acid-Schiff positivity. They had higher presenting white cell counts and serum concentrations of lactic dehydrogenase; two variables which were correlated with each other. There was a trend towards pre-B children being younger and fewer had hyperdiploid blasts, but these differences were not statistically significant. No difference from 'common' ALL in response to therapy was apparent for the pre-B patients at a median follow up time of 17 months--too short a period for any conclusion to be drawn. Other than immunophenotype, pre-B ALL has no pathognomonic features, but there are differences from C-ALL in the distribution of some disease characteristics known to be associated with a worse prognosis.