====== JAK2 V617F ======


Polycythaemia vera (PV) is a clonal proliferative disorder of the [[bone marrow]] characterized by autonomous [[hematopoiesis]], which results in a panmyelosis in the peripheral blood. It is typically characterized by an acquired mutation in [[JAK2 V617F]]. Progression to [[myelofibrosis]] (MF), characterized by worsening cytopenias and the development of constitutional symptoms, is seen in up to 10% of cases. [[Extramedullary hematopoiesis]] (EMH) in the [[spleen]] is a common finding in myelofibrotic transformation, but elsewhere in the body, it is extremely unusual. 
Randhawa et al. reported the case of a 69-year-old male whose PV progressed to secondary MF and who presented with compression of the [[thoracic spinal cord]] directly as a result of EMH. Cytogenetic and molecular findings in the bone marrow were in keeping with evolving myeloid disease. He was managed by surgical [[laminectomy]] with an excellent outcome. Extramedullary hematopoiesis may be seen in both PV and on transformation to MF. This very rare complication should be borne in mind when managing patients with [[myeloproliferative disorder]]s.
((Randhawa MS, Harrison L, Walkden J, Watson H. Spinal cord compression
secondary to extramedullary haematopoiesis in transformed polycythaemia rubra
vera. J R Coll Physicians Edinb. 2022 Mar;52(1):24-26. doi:
10.1177/14782715221088912. PMID: 36146966.)).