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Essential Thrombocythemia

Synonyms: Primary Thrombocythemia , Myeloproliferative Syndrome [Essential Thrombocythemia]

Definition

Myeloproliferative syndrome with very high platelet counts (>750 k/ul) and megakaryocytic hyperplasia; initially other cell lines are not increased.

Pathogenesis

  • Myeloproliferative disorder
  • Closely related to polycythemia vera but no increase in red cell mass1–3

Histopathology

Differential Diagnosis

Select up to 2 differential diagnoses to compare with Essential Thrombocythemia

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  • Secondary forms of thrombocytosis:
    • distinction may be difficult from routine morphologic studies
    • sensitive and specific indications of essential thrombocythemia:
      • increased megakaryocytic proliferation
      • increased angiogenesis as determined by CD34 expression
      • decreased c-mpl (thrombopoietin receptor) expression in megakaryocytes4,5

References

1 Buss DH, O'Connor ML, Woodruff RD, Richards F, Brockschmidt JK. Bone marrow and peripheral blood findings in patients with extreme thrombocytosis. A report of 63 cases. Arch Pathol Lab Med. 1991;115:475–480.

2 Imbert M, Pierre R, Thiele J, Vardiman JW, Brunning RD, Flandrin G. Essential thrombocythaemia. Jaffe ES, Harris NL, Stein H, Vardiman JW editor. World Health Organization Classification of Tumors. Pathology and genetics of tumours of haematopoietic and lymphoid tissues. Lyon: IARC Press; 2001.

3 Murphy S, Iland H, Rosenthal D, Laszlo J. Essential thrombocythemia. An interim report from the Polycythemia Vera Study Group. Semin Hematol. 1986;23:177–182.

4 Mesa RA, Hanson CA, Li CY, Yoon S-Y, Rajkumar SV, Schroeder G, et al. Diagnostic and prognostic value of bone marrow angiogenesis and megakaryocyte c-mpl expression in essential thrombocythemia. Blood. 2002;99:4131–4137.

5 Pierconti F, Teofili L, Maggiano N, Vianeli N, Ascani S, Pileri S, et al. The megakaryocyte pattern of expression of C-MPL in essential thrombocythemia correlates with thrombotic risk. J Clin Pathol. 2002;55(suppl):A7.

Last updated: 14 Mar 2006

Essential Thrombocythemia

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