Examination of Peripheral Blood Flashcards
What are the fundamental processes that lead to cytopenias?
Increased destruction of RBCs, Decreased production of RBCs, or (rarely) a combination of both.
How can we tell whether a cytopenia is due to increased destruction or decreased production?
Cytopenias resulting from increased destruction should have a compensatory hyperplasia in the bone marrow as the signaling system would stimulate increased hematopoiesis. Cytopenias resulting from decreased production would not have a compensatory hyperplasia in the marrow. Serum growth factors may be increased or decreased, and if they are increased they are not getting a response (marrow is dysfunctional).
What is aplastic anemia an example of?
Aplastic anemia is caused by autoimmune destruction of marrow precursor cells. It is a cytopenia that results from decreased production, and serum growth factor levels would be increased but have little effect due to lack of marrow precursors.
How many megakaryocytic are typically visible in a high power field (magnification)?
2-4. Greater numbers indicate increased production of platelets.
What are two manners of increased platelet destruction that result in Thrombocytopenia?
Immune Mediated Destruction and Non-Immune Mediated Destruction. Immune mediated includes autoimmune reactions (own antibodies - Immune Thrombocytopenic Purpura - ITP), Alloimmune (somebody else’s antibodies - post-tranfusion, neo-natal), and Drug-Induced (quinidine). Non-Immune mediated - disseminated intravascular coagulation (lots of blood clots) and mechanical heart valves.
What is one morphological finding common when platelet production is increased?
Giant platelets - larger than RBCs. Increased production means they don’t always have time to break apart completely. Similar finding to the larger RDW during increased RBC production. Thus, this finding hints to (but does not diagnose) increased platelet production.
If a patient CBC shows elevated WBC levels with no other abnormal findings, what is the most appropriate next test?
WBC differential
What does “left shift” mean in a neutrophil count?
It means the presence of neutrophil precursors in the circulation, indicating accelerated hematopoiesis.
What is the main differential diagnosis for a patient with very high absolute neutrophilia?
Is it Neoplastic (CML) or Reactive (leukomoid reaction, secondary to severe infection/inflammatory disease)? Both of these are diseases of increased production (granulocytic hyperplasia), so knowing the level of precursors in the marrow does not indicate one condition over the other. Other features of a marrow biopsy are helpful, however.
What are some ways that bone marrow composition and effectiveness may be influenced?
Infection/inflammation response (normal increase in WBC precursors, granulocytic hyperplasia), CML - chronic myelogenous leukemia (non-normal increase in WBC precursors, granulocytic hyperplasia), metastatic cancer - tumor development displaces marrow cells (pancytopenia), starvation (gelatinous transformation of marrow) loss of marrow cells due to malnutrition (pancytopenia)
