Immunophenotypic characterization of acute lymphoblastic leukemia in a flowcytometry reference centre in Sri Lanka

Acute lymphoblastic leukemia (ALL), is a biologically heterogeneous disease where diagnosis, treatment and prognosis is heavily dependent on the correct characterization of the immunophenotype of each case.

To describe the immunophenotypic and laboratory features of a cohort of Sri Lankan children and adults with ALL and to compare them with those reported in other series.

Records of 229 patients who were suspected of having acute leukaemia and referred for flow cytometry to the Asiri Hospital Sri Lanka, between August 2009 and October 2013 were reviewed. Referrals were from across the country including the National Cancer Institute.

Sixty seven percent were children below 12 years of age. 80% had B-lymphoblastic leukaemia (B-ALL), 20% T- lymphoblastic leukaemia (T-ALL). In children, the peak age of diagnosis was between 2-6 years in B-ALL (61%) and 3-6 years (43.7%) in T-ALL. Incidence was commoner in males in all age groups and subtypes except in the adult B ALL group where the incidence was equal. Ninety three percent of paediatric B-ALL and 67% adult B-ALL were CD10 positive common ALL. In T-ALL cytoplasmic expression of CD3 was 100%. nTdT was the most commonly expressed immature marker, in B-ALL - 91% and in T-ALL- 69%. At least one myeloid antigen was present in 34% of B-ALL cases and 60% of T-ALL cases.

This study represents the first immunophenotype based description of ALL in Sri Lanka. Age, sex distribution, ALL subtypes and the immunophenotypic profile of each subtype mirrored those of previous studies.