Bone Marrow

Question 1

What are the indications for bone marrow collection?

Answer 1

Unexplained cytopenias
Unexplained cytosis
Marrow neoplasms (staging)
Unexplained chemistry findings (hyperCa, hyperglobulinemia)
FUO
Marrow infection

Question 2

What kind of patient requires or would benefit from bone marrow evaluation?

Answer 2

Unexplained cytopenias
Unexplained cytosis
Marrow neoplasms (staging)
Unexplained chemistry findings (hyperCa, hyperglobulinemia)
FUO
Marrow infection

Question 3

What are the sites of bone marrow collection in small animals? Which are preferred in skeletally immature animals?

Answer 3

Iliac crest, femur, *humerus (adult)

Skeletally immature: iliac crest, femur (NOT HUMERUS)

Question 4

What is the difference between bone marrow aspirates and core biopsies. Are there certain indications or diseases in which one method is preferred?

Answer 4

Aspirates: Yields fragments of marrow that are smeared out and stained for cytologic evaluation

Core biopsies: Yields cylindrical section of intact marrow. LARGER needle, evaluated histologically, plus “rolled” impression cytology smear.

Question 5

What instrumentation is needed for core biopsy or aspirate collection?

Answer 5

Aspriate: Illinois or Rosenthal needle

Core biopsy: Jamshidi needle

NEED CORE BIOPSY: After multiple “dry taps”, myelofibrosis, hypoplastic marrow, metaststic neoplasia

Question 6

Be able to correctly identify and name in the correct progression, the cells of the erythroid and granulocyte lineages. What cells from these lineages are most numerous in marrow aspirates from
healthy animals?

Answer 6

Erythroid:
Rubriblast
Prorubricyte
Rubricyte
Metarubricyte
Reticulocyte
RBC

Neutrophil:
Myeloblast
Promyelocyte
Neutrophilic myelocyte
Nuetrophilic metamyelocyte
Neutrophilic band
Neutrophil

Monocyte:
Monoblast
Promonocyte
Monocyte

Question 7

What is the marrow transit time for erythrocytes, granulocytes and platelets? How does peripheral demand (e.g., health vs. times of disease) influence this number?

Answer 7

Erythrocyte: 5 days
Granulocyte: 7 days
Platelets: 5 days

BM has stores that are ready to be release when demand increases

Question 8

Why with bone marrow recovery do monocytes begin increasing in the blood before neutrophils?

Answer 8

Faster transit time (3 days vs. neutrophil 5 days)

Question 9

What are considered normal findings in bone marrow aspirates taken from healthy dogs and cats?

Answer 9

Stainable iron present in dogs but NOT CATS

Question 10

How many cells do we count when evaluating bone marrow aspirates? How is an M:E ratio generated?

Answer 10

Count 500 nucleated cells

Compare total nucleated myeloid cells to total nucleated erythroid cells

Question 11

How do you interpret an M:E ratio? What additional information is need to make the M:E ratio “meaningful”?

Answer 11

Normally between 1:1 to 2:1

Need to know actual cell count #s and CBC to be able to interpret

Question 12

If given a description of a bone marrow aspirate +/- CBC data, be able to determine which of the following are happening (erythroid hypoplasia, erythroid hyperplasia, myeloid hypoplasia, myeloid
hyperplasia, megakaryocytic hyperplasia, megakaryocytic hypoplasia)

Answer 12

.

Question 13

Be able to correctly identify some differentials for the following findings: erythroid hypoplasia, erythroid hyperplasia, myeloid hyperplasia

Answer 13

Erythroid hypoplasia: inflammation, CKD, endocrinopathy, PRCA, FelV, myelopthisis, myelofibrosis

Erythroid hyperplasia: Hemolysis, blood loss, erythrocytosis, IMHA, MDS, iron deficiency, cobalamine deficiency

Myeloid hyperplasia: depletion, IMN, FeLV, Parvo/panleuk, drugs, Ab, Myelopthis, Meylofibrosis

Question 14

Understand the concept of hypoplasia and effective and

ineffective hyperplasia.

Answer 14

Hypoplasia: not enough produced

Hyperplasia: lots produced. Appropriately = effective, inappropriately/due to disease = ineffective

Question 15

Be familiar with causes of megakaryocytic hyperplasia and hypoplasia. Of the causes of hyperplasia, which are most common?

Answer 15

Hypoplasia:
Aelective is rare (ITP), usually with other cytopenias

Hyperplasia: 
**peripheral destruction or consumption
Iron deficiency
Inflammation
Essential thrombocythemia
Secondary to myeloid leukemia

Question 16

What is general marrow hypoplasia/aplasia? Be familiar with some causes.

Answer 16

Generalized decrease in hematopoietic cells

Ddx: 
Drug induced (TMS, azothioprine)
Estrogen toxicity
Parvo/panleuk
Chronic e. Canis
Idiopathic/immune-mediated
Myelophthisis
Myelofibrosis

Question 17

What is myelofibrosis?

What is myelophthisis?

Answer 17

Myelofibrosis: marrow filled with fibrous connective tissue

Myelophthisis: displacement of hematopoietic BM tissues

Question 18

What is meant by the term leukemia? What is the difference between acute and chronic leukemias in
terms of diagnosis and laboratory findings (e.g. CBC and bone marrow data)? In terms of prognosis?

Answer 18

Neoplasms of BM-derived cells

Acute: MORE IMMATURE CELL TYPE, > 20% marrow blasts, often cytopenias, often circulating blasts, terrible prognosis (days to month)

Chronic: CELLS LOOK MORE MATURE, <20 % marrow blasts, cytosis, few or no circulating blasts, fair prognosis (1 + year)

Question 19

Name a condition other than acute leukemia that could cause >20% blasts to be present in a marrow aspirate.

Answer 19

Other cause of BM injury (toxin)

These will not have circulating blasts

Question 20

What diseases must chronic leukemias be differentiated from? Are there any cytologic features that may be present that can help?

Answer 20

Reactive “cytosis”

Look for evidence of dysplastic change

Question 21

Bone marrow evaluation is the CORNERSTONE of diagnosing acute leukemias. However, for some of the chronic leukemias we discussed, bone marrow evaluation may not even help you make the
diagnosis? Why?

Answer 21

Need to rule out other causes of cytosis

Question 22

What is different about chronic lymphocytic leukemia compared to all the other leukemias we discussed?

Answer 22

The only leukemia that may not arise from the bone marrow.

T-cll subset is through to arise from spleen with secondary marrow involvement

Question 23

What is primary myelodysplastic syndrome? What are some differential diagnoses for dysplasia seen in the marrow? Do all forms of MDS have the same prognosis? MDS in some animals progresses to what other disease?

Answer 23

Abnormalities with early progenitor cells in the marrow +/- abnormalities in marrow micro-environment.

Characterized by hypercellular marrow with peripheral cytopenias, dysplastic features in > 10% of cells, and blast count lower than needed to diagnose acute leukemia.

Need to distinguish from secondary myelodysplastic syndromes

Not all have same prognosis

Some progress to acute leukemia

Question 24

What is multiple myeloma? How is this diagnosis made? Be able to correctly identify plasma cells if
given a photomicrograph.

Answer 24

Plasma cell neoplasia

Dx made by 2/4 criteria:

1. Monoclonal gammopathy
2. Bence Jones proteinuria
3. Presence of >20% plasma cells in BM
4. Osteolytic bone lesions

Question 25

What is the difference in occurrence of marrow involvement of MCT in canine and feline patients? Is there a prognostic difference between these groups? Be familiar with some differential diagnoses for circulating mast cells in the blood of dogs and cats.

Answer 25

BM involvement more common in cat

Dogs have worse prognosis

Ddx for dogs: inflammation*, MCT neoplasms, trauma

Cats: *visceral MCT, other neoplasms, renal disease

Question 26

If you suspect metastatic carcinoma or sarcoma to the bone marrow, what type of sample should you
collect?

Answer 26

Core biopsy

Question 27

What type of marrow disorders do you think would be likely to cause peripheral pancytopenia?

Answer 27

Generalized marrow hypoplasia
Myelophthisis
Myelofibrosis