Introduction

Essential Thrombocythemia (ET) is a Myeloproliferative Neoplasm (MPN) characterized by thrombocytosis and, like others MPNs, has complications such as thrombosis, hemorrhage, splenomegaly, bone marrow failure and a possible course to acute leukemia [1]. In addition there are reports of patients with ET that have developed from thrombosis of celiac and superior mesenteric arteries [2], thrombosis of cerebral venous sinuses [3] to pericarditis [4].

In MPNs, abnormal transient myelopoiesis and, more characteristically, myelodysplastic  syndrome, there is an increase in the number of dysplastic megakaryocytes, known as micromegakaryocytes (mMK). The international Working Group on Morphology of MDS (IWGM-MDS) defined them as generally diploid, mononuclear cells with a nucleus similar in size to that of a myeloblast or promyelocyte and less than 30 µm in diameter [5].

In a study conducted by Pich, it was found that the high expression of the JAK2V617F mutation in patients with ET is associated with a higher presence of mMK in bone marrow biopsies [6]. However,little is known about the rrelationship between the presence of mMK in peripheral blood and the occurrence of such thrombotic events.

Here we present the case of a patientdiagnosed with ET, who died after successive thrombotic events, both arterial and venous, with no additional predisposing factor, in a short period of time. The large amount of mMK and the presence of the JAK2 mutation are the main peculiariaties of the case.

Case Presentation

A 55-year-old white male was admitted in November 2012 to investigate a thrombocytosis detected on a routine exam. The patient had no symptoms or any other complaint. The possible cause of thrombocytosis was identified in 2013 when the diagnosis of ET was given. The patient diagnosis complies with the WHO criteria, which are based on clinical and laboratory characteristics [7]. Their initial platelet count was greater than 450 × 109 /L, a bone marrow biopsy (BMB) confirmed the ET. The presence of the JAK2V617F mutation was also evaluated (positive)͘

Therefore cytoreductive therapy with anagrelide (0.5 mg/2 × day), hydroxyurea (1.5 mg/day) and anti-aggregative with acetylsalicylic acid (100 mg/day) was started, which maintained his platelet count controlled. The patient did not report a history of alcohol or tobacco use and did not present any other comorbidities. However, within a few months, despite the standard therapy, the ƉĂƟĞnÆš presented ulcers and thrombosis of both lower limbs, as well as ischemia of the fifth toe.