Myelodysplastic syndrome with isolated del (5q) and JAK2V617F mutation transformed into an acute myeloid leukemia.

A 66 year old female asymptomatic patient, with marked thrombocytosis, persistent for more than 6 months, and JAK2V617F mutation underwent a bone marrow (BM) biopsy to confirm the clinical suspicion of Essential Thrombocythaemia. BM biopsy showed slight dyserythropoiesis, moderate myeloid hyperplasia and marked megakaryocyte proliferation with some degree of dysplasia. A few megakaryocytes were large, with hyperlobulated nuclei; most were medium-size or small, with round and/or hypolobulated nuclei. There were 3% CD34 positive blasts and slight reticulin fibrosis (WHO MF-1). A diagnosis of Myelodysplastic syndrome with isolated del (5q) and JAK2V617F mutation was made. The patient did not received any therapy. Two years later she was admitted to the hospital because of persistent fever and severe anaemia and neutropenia. BM demonstrated marked dyserythro-, dysgranulo- and dysmegakaryopoiesis, diffuse reticulin fibrosis and excess (25%) of CD34, CD117, CD33 and MPO positive blasts. A diagnosis of acute myeloid leukaemia with myelodysplasia-related changes was made. The morphologic findings and molecular analysis suggest to consider the Myelodysplastic syndrome with isolated del (5q) and JAK2V617F mutation as a myelodysplastic/myeloproliferative neoplasia rather than a simple MDS.