CD4-MARROW FIBROSIS( ACUTE UNDIFFERENTIATED LEUKEMIA, PROBABLY EARLY MONOBLASTIC TYPE, DEVELOPING IN A PATIENT WITH MYELODYSPLASTIC SYNDROME AND BONE)

We report here a patient who presented with pancytopenia, hypercellula r bone marrow and three-lineage dysplasia associated with an increase of reticulin fibres. After a 5-month period, anaemia and thrombocytope nia progressed very rapidly and the white blood count increased showin g 45% blasts with monocytoid morphology, but cytochemically undifferen tiated in nature. The immunophenotype revealed an unusual expression o f 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 certa inty 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 mega karyocytes and cytokine production.