This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Myeloproliferative Disorders, Subject name: Pathology
Which of the following is not a myeloproliferative neoplasm? 
Select and explain. 
A. Polycythemia vera, B. Juvenile myelomonocytic leukemia, C. Chronic myeloid leukemia, D. Essential thrombocythemia
B: Juvenile myelomonocytic leukemia
Answer: B: Juvenile myelomonocytic leukemia 
Explanation: Juvenile myelomonocytic leukemia is not included in the category of MPNs (myeloproliferative neoplasms) in WHO classification Examples of myeloproliferative neoplasms: Chronic myeloid leukemia Polycythemia vera Primary myelofibrosis Essential thrombocythemia Chronic eosinophilic leukemia Activating JAK2 mutations are seen in: Nearly all cases of polycythemia vera Approx. 50% of cases of primary myelofibrosis and essential thrombocythemia BCR-ABL1 translocation seen in CML