Bone Marrow, Essential thrombocythemia [LMP98187]

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Diagnostic Modality: 
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Disease Category: 
Neoplasia
Diagnosis: 
Essential thrombocythemia
Species: 
Human
Organ System: 
White Blood Cells, Lymph Nodes, Spleen, and Thymus
Gender: 
Female
Age: 
56 years
Diagnosis Code: 
ICD-10: D47.3 | ICD-O: 9962/3
Slide Contributor Information
Hodgson, A., Hojilla, C.

Keywords

bone marrow, megakaryocytes, thrombocytosis, platelets

Clinical History

56 year old female with platelets at 1234 x 10^9/L.

Clinical Discussion

Essential thrombocythemia (ET), like the other myeloproliferative disorders, is pathogenetically defined by mutations leading to growth factor independence (most typically in tyrosine kinases encoded by JAK2 or MPL, or most recently described in the gene encoding the calreticulin protein).

Patients with ET may be asymptomatic with increased platelets (often with very large forms) being detected in the peripheral blood incidentally. Mild leukocytosis may also be seen. When the disease does clinically manifest itself, it is usually due to thrombotic or hemorrhagic events. ET is often very indolent, with a median survival up to 15 years. Transformation to AML (acute myeloid leukemia) may rarely occur.

As seen in this case, overall bone marrow cellularity is typically only mild increased, however megakaryocytes are numerous, large, and have hyperlobated nuclei. Small clusters can be seen. Overt collagenous fibrosis should not be identified, nor should bizarre or dysplastic appearing megakaryocytes.