Lecture 18: Leukemia/Myeloma Flashcards
- Neoplastic disease of hematopoietic progenitor cells in the bone marrow
- Clonal Proliferation
- Broadly characterized as lymphoid (B-cell/T-cell) or myeloid
- Further divided into acute and chronic types
Leukemia
How is Leukemia classified/diagnosed?
- Morphology
- Cytology -> individual cells
- Histology (core biopsy) -> broader picture
- Identification of malignant hematopoietic cells in the blood or bone marrow can usually be made based on morphology alone
- Clonality
- PARR -> Expansion of B-cell vs T-cells
- Immunophenotyping
- Flow Cytometry
- Recurrent cytogenetic abnormalities
- “Chromosomal spread”
(T/F) Morphology alone is insufficient for correctly classifying many leukemias
True, is insufficient for distinguishing lymphoid from myeloid leukemia
- Relatively rare, but the true incidence is unknown
- Dogs with this are usually clinically ill at initial presentation
- Clinical signs in dogs with this are often vague and nonspecific (anorexia, lethargy, fever, weight loss, shifting leg lameness, neurologic signs)
Acute Leukemia
- Neoplastic cells are seen in the peripheral blood of most dogs and cats
- Some patients may not have circulating neoplastic cells
- Exceptionally high WBC counts are generally ALL
- Cytopenias are generally present
- Most are anemic and trombocytopenic
How is Acute Leukemia diagnosed?
- can usually be made based on history, physical examination, and CBC
- Aleukemic leukemia requires a bone marrow biopsy or bone marrow aspirate
- Flow cytometry of bone marrow aspirates/blood, is required for determining immunophenotype
ALL vs Lymphoma:
- Usually sick (symptomatic)
- No/mild lymphadenopathy
- Large number of circulating blasts (usually)
- Usually CD34 positive
ALL
ALL vs Lymphoma:
- Often “healthy” (asymptomatic)
- Marked lymphadenopathy
- No/low number circulating blasts
- >70% CD34 negative
Lymphoma
Treatment for Acute Leukemia:
- Determination of a specific type of leukemia has potential prognostic and therapeutic implications
- > 50% die of sepsis or hemorrhage
- Remissions are difficult, and survival times short
- ALL - dox-based tx (remission 20-40%, survival 1-3 months)
- AML - cytosine arabinoside-based tx?
- Neoplastic clonal proliferation of small and morphologically mature-appearing lymphocytes
- Persistent, >3 months
- Often marked, peripheral lymphocytosis
- Probably most common leukemia in cats and dogs
- It is a heterogeneous disease, manifesting as a clonal expansion of morphologically mature members of any of the different lymphocyte subsets
- T-cells tend to do better
- Often an “incidental’ finding
- Commonly asymptomatic
- Clinical signs: vague and nonspecific (lethargy, reduced appetite, slowly progressive weight loss)
- Physical exam: unremarkable, or include mild generalized lymphadenopathy, splenomegaly, hepatomegaly, pale mucous membranes, and pyrexia
Chronic Lymphocytic Leukemia
What is the major diagnostic criterion for CLL in dogs?
Absolute lymphocytosis
List treatment for CLL:
- Indolent CLL - “watchful waiting”
- Progressive/complicated CLL - chlorambucil (Leukeran) and prednisone
- Responses to treatment are slow to be observed (low growth fraction of neoplastic cells)
- Systemic proliferation of malignant plasma cells or their precursors
- Usually involves multiple bone marrow sites
- Older dogs (8-9 years), cats (12-14 years)
- German shepherd dogs over-represented
Multiple Myeloma
List Pathology associated with high levels of circulating M component and/or bone infiltration:
- Bone disease
- Bleeding diathesis
- Hyperviscosity syndrome
- Renal disease
- Hypercalcemia
- Immunodeficiency
- Cytopenias
- Heart failure
How do you diagnose Multiple Myeloma?
- Bone marrow plasmacytosis
- Osteolytic bone lesions (commonly in flat bones)
- Demonstration of serum or urine M component
Treatment for Multiple Myeloma:
- Primary alkylating agents and corticosteroids
- Melphalan (generally first-line) (go to drug)
- Chlorambucil (cats?)
