Genomic landscape in KIT D816V+ advanced systemic mastocytosis

Abstract

Objective: Polycythemia Vera (PV) and Essential Thrombocythemia (ET) are chronic myeloproliferative neoplasms (MPN) characterized by frequent thrombotic complication. Thus, the important goal of therapy is to prevent thrombosis. However, there are some JAK2V617F mutation-positive patients who show bone marrow features characteristic for PV but do not meet the World Health Organization (WHO) diagnostic criteria of PV. Recently, a new definition of masked PV is proposed; which is hypothesized as the initial manifestation of MPN. Masked PV is believed to have thrombosis more frequently than PV and ET. Here, we evaluated the outcome of patients who corresponded to masked PV. Design: We reviewed our patients retrospectively who were diagnosed as PV or ET in our institute. From medical records, we evaluated the incidence of thrombosis of patients who corresponded to masked PV. Patients: Eligible patients were JAK2V617F mutated PV or ET patients who were diagnosed in our hospital according to WHO criteria. They were classified as overt PV if hemoglobin level was >18.5g/dl in males and >16.5g/dl in females. When hemoglobin level of 16.018.4g/dl in males and 15.0-16.4 g/dl in females, they were classified as masked PV. The remaining patients with>45 10/mL of platelets were diagnosed as ET. Main Outcomes Measure: The incidence of thrombosis was 17% in masked PV and this was less frequently than in overt PV or ET. Results: Among 56 JAK2V617F-mutated patients, 6 patients (11%) were classified as masked PV and all of them were males. Their leucocyte counts was lower (11300 vs 10950/mL) and platelets counts was higher (51.6 vs 61.4 10/mL) than overt PV. Median age was 60 in overt PV, 68 in ET and 47.5 in masked PV. The incidence of thrombosis was 36%, 28% and 17%, respectively. In masked PV patients of our hospital, the incidence of thrombosis was less frequently. A possible reason for that is the treatment which maintained the Hematocrit (Hct) level below 50% in masked PV patients. Conclusion: In our patients the masked PV did not show high incidence of thrombosis, possibly because of the treatment that maintained the Hct level below 50%.