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

Megaloblastoid Nucleated RBC*

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Microscopic Features:
  • Abnormally Large in size for the stage of maturation (i.e. megaloblastoid)
  • Nucleus is round and may be less mature for stage of maturation
Normal % blood-PB, marrow-BM, lymphoid tissue-LN:
  • PB: None
  • BM: None
  • LN: None
May Resemble: Differential Diagnoses:

B12 or Folate deficiency
Myelodysplastic syndrome
Acute Myeloid Leukemia
Chemotherapy-induced (e.g.Methotrexate)

Classic Immunophenotype:
  • CD45-
  • CD117-
  • CD235a (Glycophorin A) dim+
  • CD71+
  • Note: The immunoprofile can be variable and may show aberrancies
Cartoon Image:

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  • Megaloblastoid changes are also commonly noted in non-neoplastic disorders as well (e.g. B12 or Folate deficiency). Hence, interpretation of such findings should be done with extreme caution and always be interpreted in the correct context.

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