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

Hypolobated Megakaryocytes (Increased)*

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Microscopic Features:
  • 8-10x larger than a mature RBC
  • Lower nuclear to cytoplasmic ratio because of increased cytoplasm
  • Many are hypolobated (1-2 lobes) with a mature (clumped chromatin) Nucleus
  • Nucleoli are absent
  • Cytoplasm is abundant and light blue and usually lacks granules
Normal % blood-PB, marrow-BM, lymphoid tissue-LN:
  • PB: None
  • BM: Rare Scattered
  • LN: None
May Resemble:
  • Megakaryocyte (normal) [Compare]
  • Osteoclast
  • Histiocytes and macrophages (specially multinucleated forms)
  • Osteoblast
  • Hodgkin Lymphoma Reed Sternberg cell [Compare]
  • Metastatic tumor cells
  • Myelocyte [Compare]
Differential Diagnoses:

Increased numbers in bone marrow:
Reactive increase secondary to peripheral destruction of platelets
Post Chemotherapy

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

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  • Hypolobated Megakaryocytes may be dysplastic and associated with a myelodysplastic syndrome (MDS) or newly forming megakaryocytes that are the result of a peripheral destruction of platelets (e.g. ITP)

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