Zahida Qasim*, Lubna Nasim**, Roshan Parveen**
Department of Hematology Pakistan Institute of Medical Sciences (PIMS) Islamabad
Myeloproliferative Neoplasms (MPN) refer to clonal disorders of haemopoiesis that lead to an increase in the number of one or more mature red cell progeny.1 These diseases, classically identified as Chronic Myeloproliferative Disorders, have been recently re-named by the World Health Organization as Myeloproliferative Neoplasms (MPN).2 The classical MPNs include Polycythemia (rubra) Vera (PV), essential thrombocythaemia (ET) and primary myelofibrosis (PMF). They share clinical, morphological and molecular features and can transform, in their course, into one another. They are clonal disorders of plueripotent haemopoietic cell and have, a varying degree of potential to transform into acute myeloid leukemia (AML).1
Mutation and clonal expansion of a single hematopoietic stem cell leads to Polycythemia Vera3 The main features of PV is increased red-cell mass. Polycythemia Vera (PV) is one of the Philadelphia chromosomes (Ph)–negative chronic Myeloproliferative disorders (CMPDs). It is driven by oncogenic mutations that constitutively activate the JAK-STAT signal transduction pathway, such as JAK2 V617F, or exon 12 mutations or LNK mutations. Diagnosis of PV is based on the WHO criteria.4 The clinical course in most cases of Polycythemia Veraends with thrombosis or hemorrhage, but a significant number of patients transform to myelofibrosis with myeloid metaphase, myelodysplasia, or acute myeloid leukemia.5 A few cases of transformation of Polycythemia Vera(PV) to Chronic Neutrophilic Leukemia have been described.6 A long-term study (At a median follow-up of 11 years) evaluated prognostic risk factors for survival and leukemia in 327 PV patients has shown that the risk of myeloid metaplasia is three percent.7 The transformation of Polycythemia Vera (PV) in to Acute Lymphoblastic Leukemia is very rare (Only 5 cases have been reported so far).