Janus Kinase 2 V617F Mutation Is Detectable in Spleen of Patients With Chronic Myeloproliferative Diseases Suggesting a Malignant Nature of Splenic Extramedullary Hematopoiesis

Hum Pathol. 2007 Dec;38(12):1760-3. doi: 10.1016/j.humpath.2007.04.004. Epub 2007 Aug 20.


Extramedullary hematopoiesis occurs in patients with a variety of hematologic diseases, and the spleen is a common site. Extramedullary hematopoiesis is very common in chronic myeloproliferative diseases and myeloproliferative/myelodysplastic diseases. The pathogenesis of extramedullary hematopoiesis is unknown. Using JAK2 V617F mutation as a molecular marker, we assessed paired spleen and bone marrow samples of 15 patients with various types of chronic myeloproliferative diseases and myeloproliferative/myelodysplastic diseases. The diagnosis was chronic idiopathic myelofibrosis (n=8), polycythemia vera (n=3), and chronic myelomonocytic leukemia (n=4). DNA was extracted from fixed, paraffin-embedded tissue and assessed for JAK2 V617F by real-time polymerase chain reaction assay followed by melting curve analysis. Concordant JAK2 mutation was detected in the paired samples in 7 patients. A discordant result with JAK2 V617F found in the spleen but not bone marrow was noted in 1 patient. These results indicate that extramedullary hematopoiesis in patients with chronic myeloproliferative diseases and myeloproliferative/myelodysplastic diseases is a clonal process and lend support to the theory that the cells of extramedullary hematopoiesis are carried from the bone marrow.

MeSH terms

  • Adult
  • Aged
  • Bone Marrow / physiopathology*
  • Chromosome Aberrations
  • Female
  • Hematopoiesis, Extramedullary*
  • Humans
  • Janus Kinase 2 / genetics*
  • Male
  • Middle Aged
  • Mutation
  • Myeloproliferative Disorders / genetics*
  • Reverse Transcriptase Polymerase Chain Reaction
  • Spleen / physiopathology*


  • Janus Kinase 2