Abnormal chromatin clumping in leucocytes: a clue to a new subtype of myelodysplastic syndrome.

We report 6 patients with myelodysplastic syndrome, all of whom showed a bizarre nuclear anomaly within the neutrophils that was characterized by extensive clumping of chromatin into large blocks separated by clear zones, generally associated with a lack of segmentation. Anaemia, thrombocytopenia, variable leucocyte counts with leucoerythroblastic picture, marrow hypercellularity with granulocytic hyperplasia and moderate dysplastic changes in erythroblastic and megakaryocytic lines were present at diagnosis. 2 patients had normal karyotypes and a 3 showed a deletion of chromosome 14. 5 out of 6 patients had pneumonia at diagnosis. The median survival was short (5 months) and haemorrhagic complications were the cause of death in 4 patients. The clinical features and the evolution of these and other reported cases suggest that the presence of abnormal chromatin clumping in leucocytes might be a clue to a new subtype of myelodysplastic syndrome.