Application of megakaryocytic morphology in diagnosing 5q- syndrome.

In order to evaluate the diagnostic importance of the megakaryocytic morphology in the 5q- syndrome we studied the bone marrow from 48 unselected patients with myelodysplastic syndromes (MDS). 44 cases were primary and 4 secondary to cytostatic drug treatment or irradiation. There were 24 cases with chromosome anomalies, of whom 10 had del (5q). 4 of these had refractory anaemia (RA) with 5q- as the sole anomaly (group A), 2 had RA with 5q- and additional chromosome anomalies consisting of trisomy 8 (group B); 3 patients had RA with excess of blasts (RAEB) and complex, karyotypic changes also including 5q- (group B). Changes of the same type were found in 1 case of multiple myeloma with secondary MDS. All 6 RA patients with 5q- had characteristic megakaryocytes. More than 50% of the cells had no more than 2 nuclear segments, and predominantly had a diameter of 30 micron or more. No other patient with RA showed this picture. Only 1 patient with RAEB 5q- in group B had the same megakaryocytic changes. We conclude that diagnosis of a 5q- syndrome may be strongly suspected in cases of RA with these bone marrow changes. In cases of RAEB 5q- group B the bone marrow examination did not reveal the same consistent changes.