Clinical Profile of Philadelphia Negative Myeloproliferative Neoplasms in India.

BACKGROUND AND OBJECTIVES : Philadelphia negative chronic myeloproliferative neoplasms (MPN) consist of polycythemia vera (PV), essential thrombocytosis (ET) and primary myelofibrosis (PMF). Clinical information, from India, on these diseases is limited. We sought to undertake a descriptive study of these disorders with emphasis on the thrombotic complications. AIMS AND OBJECTIVES : 1. To study the clinical profile of patients with Philadelphia negative chronic myeloproliferative diseases. 2. To assess the prevalence of thrombotic events in these disorders in our population. The phenotype of the classical Philadelphia negative chronic myeloproliferative disease in India is similar to that reported in the International literature. Inclusion Criteria (All): 1. All the patients who have undergone testing for JAK2 mutation in Christian Medical College, Vellore. 2. All of these patients who can be categorized in to a specific Philadelphia negative myeloproliferative neoplasm diagnostic category, as described in the ‘WHO Classification of Tumors of Hematopoietic and Lymphoid Tissues’, Fourth Edition. An outline of this has been mentioned in the chart. 3. Patients who have been inadequately evaluated but nevertheless have some features of MPN and hence can be labeled as ‘probable MPN’. Exclusion Criteria (Any): 1. Patients who haven’t been evaluated adequately so as to be able to categorize them in to any specific diagnosis of Philadelphia negative myeloproliferative neoplasm. 2. Philadelphia chromosome positivity by conventional cytogenetics, FISH or RT PCR. METHODS : A retrospective chart review of patients who had presented to our institution and had undergone testing for JAK2 mutation analysis was undertaken. RESULTS : A total of 227 patients were analyzed and the most common diagnosis was polycythemia vera, 42%, followed by PMF 21% and ET 13.7%, and 12% of patients had probable MPN. Overall there was a male predominance (78.9%), except in patients with ET. Thrombosis (19.4%) and splenomegaly (11.7%) were the commonest presenting features. Arterial thrombosis was present in 35.77% of patients with probable MPN, 29.9% of PV and 25.8% of ET. Venous thrombosis was present in 17.8% of patients and was most frequent in ET (22.6%). The prevalence of JAK2 positivity was PV 66.7%, ET 58.1% and PMF 47.9%. Hydroxyurea and venesection were the commonest first-line treatment modalities. Most of the patients had at least a partial response to treatment. CONCLUSION : Polycythemia vera was the commonest MPN and the incidence of thrombosis was high in the group studied. JAK2 positivity in PV was lower than what has been reported