Bone marrow

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Author: Mikael Häggström [note 1]

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

Autopsy

Using pliers or similar tool, squeeze some bone marrow from a rib.

Microscopic evaluation

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

Report

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

Gross processing

  • Ensure that the biopsy is properly fixed (generally at least 2 hours).
  • Measure length and diameter of each fragment.
  • If the biopsy is received in a zinc-containing fixative, rinse it for about 2 minutes, such as placing the cassette in a container under running water (and block any sink enough so that the cassette won't float away).
Histopathology of bone marrow with insufficient decalcification, wherein the bony trabeculae may get pushed by the microtome blade and plow away the cells of interest as displayed. To compensate, thicker sections may be taken, also making evaluation harder.
  • Put in decalcifying solution, preferably using a type that is optimal for performing subsequent immunohistochemistry. Generally decalcify the specimen for about 15 minutes initially, and palpate the specimen to check whether it is still firm. If it is, decalcify another 5-10 minutes and check again. Rather have it a little bit too soft than a little bit too firm. Be careful to follow grossing guidelines for bone marrows, since even a small aberration in the processing is likely to be noticed as creating artifacts.
Gross report example
The specimen is received in AZF solution and consists of __ core needle bone marrow biopsy fragment(s) measuring __ cm in length and 0.2 cm in diameter. The specimen is entirely submitted for microscopic examination in one cassette following decalcification.

Microscopic evaluation

Evaluate the following:

Bone marrow aspirate

Find a location where bone marrow cells can be seen individually, preferably with minimal peripheral blood among them. Sometimes it is between trabeculae and sometimes it is in the surrounding area. Perform a differential count by counting 500 cells[1] and dividing the numbers by 5 to get their percentages. Don't count cells that don't have a cytoplasm or nucleus. If you receive several slides, count about the same number of cells from each slide, but don't count cells from slides where the cell types are more indistinct.

  • Myeloid/erythroid ratio, usually defined as the ratio between the number of neutrophil granulocytes and precursors versus the number of erythroblasts. Depending on source, the lower limit of the normal range for this ratio bone marrow aspirate smears in adults is 1 to 2, and the upper limit is 5 to 8.[2] In histologic sections, the normal range is 1.5 – 3.0.[2] Some hematologists also include eosinophils, basophils and monocytes, as well as their precursors, in the myeloid number, but this has only a minor effect on the M:E ratio in normal individuals.[2] Still, if you are to calculate the value for a senior, check their preference first.

In a bone marrow count, nucleated red blood cells count into the total percentage of cells (but does not count into percentage of white blood cells in peripheral blood).

Bone marrow biopsy, H&E stain
  • Adequacy: There should preferably be 5 intertrabecular spaces.
  • Cellularity: This is a rather rough estimation of the area of hematopoietic cells divided by the area of all intertrabecular matter, which otherwise mainly consists of fat cells and a small interstitial space. Areas of bone, hemorrhage or artifacts are not counted. 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.
  • Look for any granuloma or cancer metastasis
Bone marrow biopsy, other stains

Generally including:

Ring sideroblast, defined by five or more perinuclear iron granules that encompass at least 1/3 of the nuclear circumference.[3]
  • Iron stain: Look at approximately 100 cells and semi-quantify the presence of any ring sideroblasts.
  • Reticulin to grade the amount of fibrosis.
  • CD3 and CD20 to highlight T and B cells, respectively.

Microscopic report

Example template:

On this resource, the following formatting is used for comprehensiveness:

  • Minimal depth
  • (Moderate depth)
  • ((Comprehensive))
Other legend

<< Decision needed between alternatives separated by / signs >>
{{Common findings / In case of findings}}
[[Comments]]
Link to another page

SOURCE:

Bone marrow aspirate and biopsy

CLINICAL INFORMATION:

{{Lymphocytosis / Pancytopenia / Anemia etc }}

DIAGNOSIS:
PERIPHERAL BLOOD:

{{Lymphocytosis / Pancytopenia / Anemia etc }}

BONE MARROW, {{POSTERIOR ILIAC CREST,}} ASPIRATE AND BIOPSY:

{{Chronic/Acute lymphocytic/myeloid leukemia.}}
See description and comment.

GROSS DESCRIPTION:

[[As per gross report above.]]

MICROSCOPIC DESCRIPTION:

PERIPHERAL SMEAR:

MORPHOLOGY:

  • Red Blood Cells: No significant abnormality.
  • White Blood Cells: No significant abnormality.
  • Platelets: No significant abnormality.

BONE MARROW ASPIRATE:

Left / RIGHT / UNDESIGNATED SITE

CELLULARITY ESTIMATE: Adequate. / Hypocellular and hemodilute. / Hypercellular. / Too few cells for morphologic evaluation.

MARROW DIFFERENTIAL

  • Erythroblasts: __%
  • Blasts: __%
  • Neutrophils/precursors: __%
  • Eosinophils: __%
  • Basophils: __%
  • Lymphocytes: __%
  • Monocytes: __%
  • Plasma Cells: __%
  • M:E ratio: __:__

ERYTHROPOIESIS: Maturing.

GRANULOPOIESIS: Maturing.

MEGAKARYOCYTES: Present.

LYMPHOCYTES: Mature.

PLASMA CELLS: Rare without atypia.

BONE MARROW TOUCH PREPARATION: _

BONE MARROW BIOPSY:

Left / RIGHT / UNDESIGNATED SITE

SPECIMEN ADEQUACY:

Satisfactory. / Limited. / Unsatisfactory.

CELLULARITY:_

_%: Normocellular / Hypercellular / Hypocellular for age. / Variable ( _ %- _ %, overall _ %) / Cannot assess cellularity due to small biopsy. {{With aspirative artifact.}}

Decalcified bone marrow biopsy demonstrates ____________________

BM Erythropoiesis _

BM Cellularity _

BM Megakaryocytes _

BM Myelopoiesis _

BONE MARROW IRON STAIN: Storage iron _/4 on aspirate smear with / without ring sideroblasts.

SPECIAL STAINS:

Reticulin Stain: ___ reticulin fibrosis (_+/3+)

FLOW CYTOMETRY:

No immunophenotypic evidence for abnormal myeloid maturation, an increase in blasts, or a lymphoproliferative disorder (see attached report).

COMMENT:

{{Cytogenetic study and next generation sequencing panel for myeloid neoplasm are pending.}}
All stains have functional controls.


See also

Notes

  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.

Main page

References

  1. Abdulrahman AA, Patel KH, Yang T, Koch DD, Sivers SM, Smith GH (2018). "Is a 500-Cell Count Necessary for Bone Marrow Differentials?: A Proposed Analytical Method for Validating a Lower Cutoff. ". Am J Clin Pathol 150 (1): 84-91. doi:10.1093/ajcp/aqy034. PMID 29757362. Archived from the original. . 
  2. 2.0 2.1 2.2 BJ. Bain (2017-02-19). Chapter 5: Pathology of the marrow. Basicmedical Key.
  3. Salama M, Teruya-Feldstein J, Kremyankaya M. Atlas of Diagnostic Hematology. Philadelphia, PA: Elsevier; 2021.

Image sources