A rare morphological and immunophenotypic presentation of adult B-cell acute lymphoblastic leukemia with blasts in the monocytic zone on CD45 side scatter

ABSTRACT

We present a case of B-acute lymphoblastic leukemiain an elderly patient who presented with severe weakness and pancytopenia. The patient was a 75 year old Female whose blasts had an unusual morphology in form of coarse azurophilic granules and cytoplasmic blebs and on flow cytometry the blasts were present in the bright CD45 zone with a high side scatter. Bone marrow aspirate sample was subjected to multicolour flow cytometry using Beckman Coulter Navios® which is an 8 colour flow cytometer.Flow cytometricanalysis of the bone marrow aspirate showed blasts in the monocytic zone with a precursor B cell immunophenotype. Complete blood counts showed pancytopenia with peripheral blood film not showingany blasts. Bone marrow aspirate smears showed 20% blasts with coarse azurophilic granules and cytoplasmic blebs.The position of the blasts in this case which were in monocytic zone giving them a bright expression of CD45 and a high side scatter on the CD45 side scatter. This is not the usual positionfor blasts in B-acute lymphoblastic leukemia as these blasts are less complex. A bright expression of CD45 by blasts in B-acute lymphoblastic leukemia is known to be associated with a poor prognosis but the clinical significance of blasts being bright CD45 with a high side scatter is a very rare occurrence and more number of cases with a similar presentation are required to determine a prognostic significance.