Bone marrow

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Author: Mikael Häggström [notes 1]

Bone marrow aspirate showing normal "trilineage hematopoiesis":
- Myelomonocytic cells: an eosinophil myelocyte marked
- Erythroid cells: an orthochromatic erythroblast marked
- Megakaryocytic cells.


Microscopic evaluation

  • Confirm trilineage hematopoiesis (see image).
  • Look for apparent cellular atypia or decrease of cellular diversity.


Example in a normal case:

Bone marrow from rib (or other location if applicable): Trilineage hematopoiesis. There is no evidence of malignancy.

Bone marrow biopsy

Evaluate the following:

  • Adequacy: There should preferably be 5 intertrabecular spaces.
  • Cellularity: In patients 20-80 years, the percentage should be about 100 minus age, such as 40% in a 60 year old patient.
  • Thrombopoiesis: There are normally about 3 megakaryocytes per 40x field.
  • Myeloid/erythroid ratio, normally 3-4 myeloid cells per erythroid cell.
  • Look for any granuloma or cancer metastasis


  1. For a full list of contributors, see article history. Creators of images are attributed at the image description pages, seen by clicking on the images. See Patholines:Authorship for details.

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