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

Staghorn-shaped Megakaryocyte*


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› Microscopic Features:

• 10-30x larger than a mature RBC
• Lower nuclear to cytoplasmic ratio because of increased cytoplasm
• Multilobated Nucleus (6-10 lobes with a Staghorn configuration)
• Nucleoli are absent
• Cytoplasm is abundant and light blue which usually lacks granules

› Normal % blood-PB, marrow-BM, lymphoid tissue-LN:

• PB: None
• BM: None
• LN: None

› May Resemble:

• Megakaryocyte (normal) [Compare]
• Osteoclast
• Histiocytes and macrophages (specially multinucleated forms)
• Hodgkin Lymphoma Reed Sternberg cell [Compare]
• Metastatic tumor cells

› Differential Diagnoses:

Associated with: Myeloproliferative neoplasm (specifically Essential Thrombocythemia) Post Chemotherapy MDS (rarely)

› Classic Immunophenotype:

• CD41+
• CD42+
• CD61+

› Cartoon Image:


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› Misc:

• For Megakaryocytes with polar disconnected lobes think of MDS For Megakaryocytes with Staghorn shape think of Essential Thrombocythemia (a Myeloproliferative neoplasm)