Pre-B and 'common' lymphoblastic leukaemia of childhood compared.

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.