Essential thrombocythaemia with mutation in : clinicopathological correlation and comparison with 2V617F-mutated and mutated genotypes.

AIM

To characterise the clinical and histological features of -mutated essential thrombocythaemia (ET).

PATIENTS AND METHODS

Bone marrow biopsies of 175 patients with ET were centrally reviewed according to the 2016 WHO classification, including 42 cases with mutation, 98 V617F-mutated and 35 -mutated. Clinical and histological features were compared among the three genotypes included in the current 2016 WHO classification and among the different types of mutations.

RESULTS

Patients with -mutated ET were significantly older than those with the other genotypes. Haematological values at diagnosis were similar among -mutated and -mutated ET, with both genotypes showing higher platelet counts and lower haemoglobin values than ET with V617F genotype. In the bone marrow, the median number of megakaryocytes was higher in and than in V617F genotype (16, 19 and 14 megakaryocytes per ×20 power field, respectively, p=0.004). Histological features of prefibrotic myelofibrosis were rarely observed in genotype, whereas sinusoidal hyperplasia, dense clusters of megakaryocytes and reticulin fibrosis were more frequent in -mutated ET, with 11% of such cases fulfilling WHO 2016 histological criteria of prefibrotic myelofibrosis. With a median follow-up of 3.5 years, no significant differences were seen among genotypes regarding survival, vascular complications or myelofibrotic transformation. There were no significant differences in the clinical data or in the histological characteristics depending on the type of mutation.

CONCLUSION

and ET genotypes share clinical and histological characteristics. In contrast to genotype, features of prefibrotic myelofibrosis are uncommon in -mutated ET.