Hemostasis 4 Flashcards
What are 4 causes of lymphopenia?
- immunodeficiency (HIV, DiGeorge)
- High cortisol state (exogenous corticosteroids, Cushing syndrome)
- Autoimmune destruction (SLE–Abs against blood cells)
- Whole body radiation
How does a high cortisol state lead to lymphopenia?
corticosteroids induce apoptosis of lymphocytes
Infectious mononucleosis is caused by infection with what pathogen?
EBV
less commonly, CMV
What is infectious mononucleosis?
EBV infection that results in a lymphocytic leukocytosis comprised of reactive CD8+ T cells
How is EBV transmitted?
Via saliva
What cells/structures does EBV primarily infect?
- oropharynx (–> pharyngitis)
- liver (–> hepatitis, hepatomegaly, inc. liver enzymes)
- B cells
The CD8+ T cell response to EBV infection leads to what clinical manifestations?
- Generalized lymphadenopathy (multiple nodes, due to T-cell hyperplasia in the lymph nodes paracortex)
- Splenomegaly (T cell hyperplasia in the periarteriolar lymphocyte sheath)
- High WBC count with atypical lymphocytes (reactive CD8+ T cells)
What test is used for screening in a person suspected to have mononucleosis?
The monospot test
What does the monospot test detect?
IgM antibodies that cross react with horse or sheep RBCs (heterophile antibodies)
usually turns positive within one week after infection
What does a negative monospot test suggest?
- The patient does not have infectious mononucleosis
- CMV (instead of EBV) might be the cause of the IM
- We tested too early, and the test is giving us a false negative.
How do you make a definitive diagnosis for infectious mononucleosis?
Serologic testing for the EBV viral capsid antigen
What are 3 complications of EBV infectious mononucleosis?
- inc. risk of splenic rupture (patients advised to avoid contact sports for one year)
- Rash if exposed to ampicillin
- Dormancy of virus in B cells –> inc. risk of recurrence and B cell lymphoma, esp. if immunodeficiency develops.
What is acute lymphoblastic leukemia?
A neoplastic proliferation of lymphoblasts (>20%) in the bone marrow.
In which demographic does acute lymphoblastic leukemia most commonly arise?
Children.
It is associated with Down Syndrome (usually arises after the age of 5)
Into what broad groups can ALL (acute lymphoblastic leukemia) be subclassified?
B-ALL and T-ALL
B-ALL is most common
What is the characteristic histologic marker for lymphoblasts?
positive nuclear staining for TdT, a DNA polymerase
What cell markers are used to characterize B-ALL
–positive nuclear staining for TdT
–CD10, CD19, and CD20
Upon what information is the prognosis for B-ALL usually made?
The prognosis is typically based on cytogenic abnormalities:
–t(12;21) has a good prognosis (more common in children)
t(9;22) has a poor prognosis (more common in adults)
What cell markers characterize T-ALL?
positive nuclear staining for TdT
CD2-CD8
Myeloblasts are usually characterized by positive staining for what?
myeloperoxidase (MPO)
MPO can form crystal aggregates calles Auer rods.
What is chronic lymphocytic leukemia (CLL)?
A neoplastic proliferation of naive B cells that co-express CD5 and CD20.
These cells enter the blood stream and lymph nodes
What is seen on PBS in chronic lymphocytic leukemia?
Increased #s of lymphocytes and smudge cells
What are 3 complications of chronic lymphocytic leukemia?
- Hypogammaglobulinemia
- Autoimmune hemolytic anemia
- Transformation to diffuse large B-cell lymphoma
If chronic lymphoblastic leukemia involves a proliferation of naive B cells, why do w see complications of hypogammaglobulinemia and immune hemolytic anemia?
Normally, B cells will mature to become immunoglobin-producing plasma cells. However the neoplastic B cells in chronic lymphocytic leukemia do not produce Ig. When they do, they often do a bad job, and end up producing antibodies against the patient’s own RBCs –> autoimmune hemolytic anemia.