Momen A. Zaid^1,, Oadi N. Shrateh², Mariam Thalji², Yara Assaf²

Essential thrombocythemia (ET) is considered a classic” BCR-ABL1-negative chronic myeloproliferative condition (MPD) that’s characterized by thrombocytosis, bleeding, and/or thrombosis. It usually affects the megakaryocytic cell lineage. While the disease is most commonly observed in people between the ages of 50 and 60, ET is an extremely rare myeloproliferative disorder in the pediatric age group. In children under the age of 14, the annual incidence of ET is estimated to be 1 per 10 million, approximately 60 times lower than older ages. Most ET patients, especially children are asymptomatic and discovered incidentally while doing investigations for other reasons. Herein, we introduce a very rare case of essential thrombocythemia in a 5-year-old male patient that was detected incidentally following receiving the influenza vaccine. The patient had a persistent elevated platelet count over 450x109 /L. Bone marrow showed markedly increased megakaryocyte number. Genetic testing and bcr/abl rearrangement were unremarkable. The patient showed no symptoms during the period of follow-up.