The syndrome of abnormal chromatin clumping in leucocytes: a myelodysplastic disorder with proliferative features?

Five patients presenting extremely exaggerated chromatin clumping in leucocytes, associated with a loss of segmentation, are described. Peripheral cytopenia, a high percentage of circulating immature granulocytes (chiefly myelocytes) with variable leucocytosis, marrow hypercellularity with granulocytic hyperplasia and moderate dysplastic changes in erythroblastic and megakaryocytic lines, constitute, together with the granulocytic nuclear anomaly, the characteristic features of the studied cases. Cytogenetic analysis showed a clonal 12p anomaly in one of the three cases available for study. Survival was poor with a median of 15 months, bleeding and infections being responsible for the majority of deaths. All these findings point to abnormal chromatin clumping in leucocytes as the marker of a true entity with both myelodysplastic and myeloproliferative features. We propose that it take its place among myelodysplastic syndromes (MDS) beside chronic myelomonocytic leukaemia (CMML), with which it shares many similarities in clinical and biological behaviour.