Aberrant increase in the immature platelet fraction in patients with myelodysplastic syndrome: a marker of karyotypic abnormalities associated with poor prognosis.

Some patients with myelodysplastic syndrome (MDS) show a marked increase in the percentage of immature platelet fraction (IPF%) despite the absence of severe thrombocytopenia. To determine the significance of such an unbalanced increase in the IPF%, we investigated the IPF% and other laboratory findings of 51 patients recently diagnosed with MDS. Subjects consisted of 80 healthy males, 90 healthy females, and 51 patients with MDS and 20 patients with idiopathic thrombocytopenic purpura (ITP). The IPF and IPF% were determined using a Sysmex XE-2100 system loaded with IPF Master software (XE IPF Master, Sysmex). Platelet counts were measured simultaneously. IPF% and platelet counts of these patients ranged from 1.1% to 25.1% (median, 5.3%) and from 6 to 260 x 10(9)/L (median, 71 x 10(9)/L), respectively. Twelve patients showed platelet counts more than 50 x 10(9)/L with 10% or more IPF%. All of the 12 patients had chromosome abnormalities including monosomy 7 and complex abnormalities involving 7 or 5q. In the other 39 patients who did not show the aberrant IPF% increase, chromosomal abnormalities were seen only in seven patients and none of them had chromosome 7 abnormalities. The IPF% of two patients increased to more than 10% in association with the appearance of monosomy 7. These findings suggest that a high IPF% in MDS patient may be a marker for karyotypic abnormalities with a poor prognosis, including chromosome 7 abnormalities.