The median platelet count of the patients was 943 x 10⁹/L (range 690 to 1340). Twenty-nine patients had platelet counts greater than 1000 x 10⁹/L. The median white blood cell (WBC) count was 13.5 x 10⁹/L, with more than 3% basophils in 13 patients. The packed cell volume (PCV) was lower than 0.52 L/L in all patients. The LAP score was increased in 47 patients and normal in nine. Bone marrow examination showed megakaryocytic hyperplasia and dysmegakaryocytic features in all cases, with myelofibrosis present in two patients. Splenomegaly was noted in eight patients. Thrombotic events occurred in only three patients. The follow-up period was 3 to 115 months (median 63 months), and transformation into acute leukemia was observed in only one patient.

The BCR-ABL transcripts were detected by RT-PCR in two patients (3.6%). One patient carried both the b2/a2 and b3/a2 isoforms, while the other carried only the b3/a2 isoform. The RT/PCR amplification of ABL transcripts yielded the expected product in all cases, confirming the integrity and quality of the RNA samples. No differences were observed with respect to any investigated clinical or laboratory feature between the BCR-ABL-positive and BCR-ABL-negative patients (Table 1).