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Atlas of Bone Marrow pathology
Mojmir Moulis, Josef Feit et al.
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+ Bone Marrow Pathology
Essential Thrombocythemia (ET)
Clinical signs
  • primarily affects the proliferation of megakaryocytes
  • thrombocytosis: abnormal hemorrhage, epistaxis, thrombosis
  • prognosis: indolent disorder, median survival time is 10 – 15 years, less than 5% of patients develop MDS or AML
Etiology

Approx. 40 – 50% of patients carry the somatic JAK2 V617F mutation, qpprox. 1% carry the MPL W515K/L mutation.

Histology

Normocellular bone marrow, increased numbers of clusters formed by huge megakaryocytes, which have hyperlobated stag-horn and cloudy nuclei, M : E ratio is normal (2 – 3 : 1), no or only slight fibrosis.

Pictures

Essential thrombocythemia, bone marrow: Essential thrombocytopenia, bone marrow, HE 100x (72624)