Tehran University of Medical Sciences Case Reports in Clinical Practice 2538-2683 6 4 2021 11 27 141 144 Mehrdad Payandeh Department of Hematology and Medical Oncology, Kermanshah University of Medical Sciences, Kermanshah, Iran. Mehrnoush Aeinfar Medical Biology Research Center, Kermanshah University of Medical Sciences, Kermanshah, Iran. Kimiya Dadashizadeh Department of Biology, Faculty of Science, University of Maragheh, Maragheh, Iran. saba yari Department of Biology, Faculty of Science, University of Maragheh, Maragheh, Iran. 2020 08 25 2020 09 29 Immune Thrombocytopenia (ITP) is an autoimmune bleeding disorder. Tyrosine Kinase JAK2 (JAK2 V617F) mutation occurs in nearly 60% of Essential Thrombocythemia (ET) patients. Both diseases produce impaired platelet. We describe a case with ET following ITP. So far, only 3 reports described ET following ITP. We report the fourth patient with JAK2 V617F mutation at the onset of ITP presented 20 years ago that needed splenectomy. The association of these two diseases may recommend similar pathogenic mechanisms between Myeloproliferative Neoplasms (MPNs) and ITP that should be further explored. https://crcp.tums.ac.ir/index.php/crcp/article/view/400