Acute Lymphoblastic Leukaemia in Infancy: Clinical and Biological Features

The clinical and biological features of nineteen unselected cases of infant acute lymphoblastic leukaemia (ALL) are presented. All infants, eight male and eleven female. were 1 year of age or less at presentation of their disease and all showed the typical clinical features of ALL in infancy: hyperleucocytosis, organomegaly, frequent central nervous system (CNS) disease and one infant had cutaneous lesions. In the 17 cases which were successfully karyotyped, translocation of chromosome 11 involving band q23 were demonstrated in 16 cases (94%). The majority fell into the B precursor, or "null" ALL, category (CD10 negative, but CD19 and HLA DR positive), two cases, however, showed concomitant expression of B cell and myeloid (CD13 and CD33) markers. Two cases were CD10, HLA DR and CD19 positive and in one of these as well as one of the CD10 negative cases, 25-30%, of the blast cells expressed cytoplasmic Ig, M, a characteristic of pre-B cells. All cases, irrespective of phenotype or karyotype, showed rearrangement of the immunoglobulin heavy chain genes (IgH), but no light chain rearrangement. Together with the expression of B cell associated markers this, provided good evidence of their B lineage. No rearrangements of the β or γ chains of the T cell receptor complex (TcR) were seen in any case, nor was any rearrangement of the insulin receptor, which maps to band 19p13, seen in the cases with the t(11;19) translocation. The prognosis was uniformly poor. The majority of cases relapsed rapidly in the bone marrow whilst on therapy and within the first six months after diagnosis. Within the group of 19 infants studied, those with the t(11;19) translocation appeared to form a subgroup with the worst prognostic features (WBC averaging 591 × 10(9)/1, profound organomegaly and proven CNS disease in 4/7). 4/7 of this subgroup received no treatment and of the three who were treated, two relapsed within the first 11 months of treatment.