CD4+ Acute Undifferentiated Leukaemia, Probably Early Monoblastic Type, Developing in a Patient with Myelodysplastic Syndrome and Bone Marrow Fibrosis

Abstract

We report here a patient who presented with pancytopenia, hypercellular bone marrow and three-lineage dysplasia associated with an increase of reticulin fibres. After a 5-month period, anaemia and thrombocytopenia progressed very rapidly and the white blood count increased showing 45% blasts with monocytoid morphology, but cytochemically undifferentiated in nature. The immunophenotype revealed an unusual expression of CD4, CD36 and HLA-DR in the absence of any other myeloid or lymphoid lineage-associated markers. The patient died unexpectedly during the course of chemotherapy. The occurrence of CD4, CD36 and HLA-DR on the blast cells cannot determine the lineage of differentiation with certainty but provides some evidence that the leukaemic cells were probably derived from a very early monocytic progenitor with maturation arrest. These cells had apparently complex interactions with pathologic megakaryocytes and cytokine production.

Key Words:

• Myelodysplasia with myelofibrosis
• acute unclassified leukaemia
• CD4
• CD36