eng Science and Education Publishing American Journal of Medical Case Reports 2374-216X 2023-03-07 11 3 55 59 10.12691/ajmcr-11-3-4 AJMCR20231134 article Momen A. Zaid momen.a.zaid@gmail.com 1 Oadi N. Shrateh 2 Mariam Thalji 2 Yara Assaf 2 Research and Clinical Teaching Assistant, Faculty of Medicine, Al-Quds University, Jerusalem, Palestine Faculty of medicine, Al-Quds University, Jerusalem, Palestine Essential thrombocythemia (ET) is considered a classicĄ± BCR-ABL1-negative chronic myeloproliferative condition (MPD) thatĄŻs 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. http://pubs.sciepub.com/ajmcr/11/3/4/ajmcr-11-3-4.pdf essential thrombocythemia