Stroke, Carotid Thrombosis and Other Thrombotic Events in Essential Thrombocythemia Patient with a High Quantity of Micromegakaryocytes

Abstract

Essential thrombocythemia is a myeloproliferative neoplasm characterized by thrombocytosis and possible complications such as thrombosis, hemorrhage, splenomegaly, bone marrow failure and acute leukemia. In the myeloproliferatives neoplasms, there is an increase number of dysplastic megakaryocytes, known as micromegakaryocytes and there is an association between the high expression of the JAK2V617F mutation and the presence of micromegakaryocytes in bone marrow. To date, reports and researches involving essential thrombocythemia and micromegakaryocytes are exceedingly scarce. We report a peculiar and unique case of a death of a 55-year-old man, due to stroke and carotid thrombosis, preceded by successive thrombotic events in a patient with essential thrombocythemia, JAK2 positive, with no additional risk factor, who did not respond well to standard treatment and had a high amount of circulating micromegakaryocytes in peripheral blood. This case goes beyond the known prognosis of ET and raises the discussion of new prognostic markers, such as the quantification of micromegakaryocytes and reaffirms the importance of the JAK2 mutation in the evolution of the disease. We also discuss the involvement of micromegakaryocytes in the probable mechanisms leading to our patient’s thrombotic state.