Primary Hematopoietic and Lymphoid Tissue ›› Bone Marrow ›› Abnormal

Megakaryoblast (Increased)*

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Microscopic Features:
  • 3-4x larger than a mature RBC
  • High nuclear to cytoplasmic ratio
  • Round Nucleus with immature chromatin (not clumped)
  • Prominent nucleoli
  • Cytoplasm is pale blue with occasional cytoplasmic blebs (want-to-be platelets)
Normal % blood-PB, marrow-BM, lymphoid tissue-LN:
  • PB: None
  • BM: Rare (<1%)
  • LN: None
May Resemble: Differential Diagnoses:

If in blood or increased numbers in bone marrow:
Acute Megakaryoblastic leukemia (AML-M7)
Transient Myelopoeisis (usually asosciated with some newborns with Down Syndrome)

Classic Immunophenotype:
  • CD41+
  • CD42+
  • CD61+
Cartoon Image:

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  • Transient Myelopoeisis shows increased megakaryoblasts in blood and/or marrow of a newborn down syndrome patient and may mimic an AML-M7 (Acute Megakaryoblastic Leukemia)

Content Editors/Website Administrators:
Hooman H. Rashidi, MD; John C. Nguyen, MD