Clin Path 16: Bone marrow disease

Rib, sternum (site of choice in horse), wing of ilium, trochanteric fossa, proximal humerus

Sites for bone marrow collection

Bicytopenia

Two cell lines affected

Pancytopenia

All cell lines affected

Hypercalcemia, atypical or immature cells in circulation, decrease in blood cell line, severe increase in blood cell line, marked hyperproteinemia (marked hyperglobulinemia)

When should we consider bone marrow disease?

Within last 24 hours

When must you submit a blood sample or CBC data?

Cytology

Bone marrow collection method

Better for cell morphology

Biopsy

Bone marrow collection method

Gives overall architecture

Marrow necrosis

Myelofibrosis (bone marrow replaced by collagen or reticulum fibers— dry tap (nothing comes out during collection))

Osteolysis/bone changes

Hypercalcemia

Neoplastic infiltration of bone marrow

Localized bone resorption

Hematopoietic and non-hematopoietic

Decreased cell numbers

1. Anemia

   1. Non-regenerative

2. Leukopenia

   1. Usually neutropenia

   2. No left shift

3. Thrombocytopenia

   1. No large or giant platelets

Increases

More cell lines involved ___ suspicion

• Bicytopenia

• Pancytopenia

Decreased cell numbers

1. Infectious: FeLV, EIAV, parvo, bacterial sepsis

2. Toxins: Chemotherapy, estrogen, phenylbutazone, bracken fern

3. Immune-mediated disease

4. Endocrine disease: hypothyroidism, hypoadrenocorticism

5. Neoplasia

Severe increase in cell numbers

1. Leukemia, lymphoma

Leukemia

1. Neoplasia of hematopoietic cells

   1. Immature cells = acute

   2. Mature cells = chronic

   3. +/- Other cell lines decreased

      1. Myelophthisis: Replacement of hematopoietic tissue by abnormal tissue

      2. Cytokine production

   4. Originates in bone marrow

Lymphoma

1. Can circulate

2. Stage V lymphoma

3. Use clinical history/exam

4. Looks the same as acute lymphoid leukemia in circulation

Severe increase in cell numbers

1. Erythrocytosis and nucleated red cells

   1. Erythroid leukemia

   2. Heat stroke

   3. Chemotherapy

2. Thrombocytosis

   1. Marked

      1. >1,000 x 10³/microliter

      2. Megakaryocytic leukemia

3. Marked hyperglobulinemia

   1. Lymphoid neoplasia

Marked hyperglobulinemia

1. Lymphoid neoplasia

   1. Lymphoma

   2. Multiple myeloma (plasma cell origin)

   3. Acute or chronic lymphoid leukemia

Normo-

Normal cellularity

Hypo-

Decreased cellularity and numbers

Hyper-

Increased cellularity and numbers

Ineffective production

Hyperplasia without expected peripheral response

1. Immune-mediated disease

2. Iron deficiency

Maturation arrest

Cell line does not go to completion

1. Immune-mediated disease

Aplasia

Lack of a cell line

Aplastic anemia

1. Generalized marrow hypoplasia

2. All cell lines affected

3. Aplastic pancytopenia more appropriate

Pure red cell aplasia

1. Only erythroid line affected

   1. Primary

      1. Immune-mediated

   2. Secondary

      1. FeLV

      2. Parvovirus