36 - Pathology of WBCs I Flashcards
What are the three types of WBC disorders?
Leukopenia
- Neutropenia
- Agranulocytosis
Reactive proliferations of WBCs
- Leukocytosis
- Lymphadenitis
Neoplastic proliferation of WBCs
- Lymphoid neoplasm ***
- Myeloid neoplasm (leukemia)
- Langerhans cell histocytosis
What is the focus of these lectures?
Lymphoid neoplasm
This is LYMPHOMA + LEUKEMIA ***
Define lymphoma
Lymphoid neoplasms arising as discrete masses
THERE IS A MASS
Define leukemia
Lymphoid or myeloid neoplasms with involvement of blood and bone marrow
THERE IS NO MASS
Why is this only a general rule?
Lymphoma can progress to a late stage where there is involvement of the blood and bone marrow, so then lymphoma would include leukemia
Leukemia is a blood and bone marrow cancer, but lymphoid can also be involved in later stages
When lymphoma is suspected, what are the different tools for diagnosis?
- Hematoxylin and eosin staining (H&E)
- Immunophenotyping***
- Cytogenetics/FISH (to identify chromosomal aberration)
- Molecular diagnostics (PCR to detect monoclonal population and neoplastic lymphoid population)
Describe immunophenotyping
This is the main method for diagnosis
- Consists of identifying the cell type
- This is done by looking at protein expression
- Done by immunohistochemistry and flow cytometry
What are the important things to look at in the clinical presentation of a lymphoma patient?
- Age
- Location
- Multiple or single sites of involvement (one lymph node or many)
What is the clinical presentation of a lymphoma patient?
- PAINLESS, non-tender lymphadenopathy (big lymph nodes***)
- Fatigue
- Malaise
- Night sweats
- Fever***
- Weight loss
What is the first step in diagnosis?
Get a biopsy if you are suspecting lymphoma
Start with an H&E stain
What are you looking for on the LOW POWER H&E stain?
Low power evaluation
- Is the lymph node architecture preserved?
Or is it effaced? (loss of B and T cell area)
- If it is effaced, what is the pattern of the atypical proliferation? Nodular, diffuse, both?
What are you looking for on the HIGH POWER H&E stain?
Do all the cells look similar?
MONOMORPHIC ***
Are there multiple cell types?
POLYMORPHIC***
KNOW THIS TERMINOLOGY
Also look at: (just know the stuff above, this is extra)
- Size (small, medium, large)
- Nucleus (irregular, regular, round)
- Chromatin (clumped, vesicular, open)
- Cytoplasm (abundant/scant, color)
How do you determine if a lymphoid neoplasm consists of mature or immature neoplasms?
Look at the morphology and immunophenotype
Immature lymphoid cell = lymphoblasts
Mature lymphoid cell = mature (peripheral) lymphoma
Describe the general trend in immunopheonotypes
B cell marker
- CD20
T cell marker
- CD3
What are the B cell markers that you need to know?
- CD19
- CD20
- Lamda light chain positive
What is the purpose of cytogenetic/molecular analysis
- You can determine whether or not a population is monoclonal
- It can extrapolate patients into prognostic categories
- Allows you to determine therapeutic targets
This is not highly tested, focus on immunophenotypes
Why do the classifications of tumors change a lot?
- It is very complex and complicated
- WHO put out a classification of tumors of hematopoietic and lymphoid tissues in 2001, edited in 2008
How does the WHO classify lymphomas?
Identify specific entities using a multiparametric approach
- Clinical features
- Morphology
- Immunophenotype
- Cytogenetics
- Molecular analysis
What are all the different types of lymphoma covered in these two lectures?
Mature (peripheral) lymphoid neoplasms
- B cell lymphomas (follicular, Mantle cell, Burkitt’s)
- T cell lymphomas (adult T-cell leukemia/lymphoma, mycosis fungoides/Sezary syndrome)
Immature (precursor) T cell neoplasms
- T lymphoblastic leukemia/lymphoma
- Anaplastic large T cell lymphoma
Why is lymphoma relevant to study?
- Lymphoma is the most common tumor type found in 10-14 year olds and 15-19 year olds
How do we determine the staging of lymphoma?
** NEED TO KNOW ***
Stage I
- Single lymph node region or extralymphatic site
Stage II
- Two or more lymph node regions or extralymphatic sites on the SAME side of the diaphragm
Stage III
- Lymph node regions or extralymphatic sites are found on BOTH sides of the diphragm
Stage IV
- Disseminated or diffuse involvement of one or more extralymphatic sites
If you see an A or B next to the stage. what does it mean?
Whether or not it is symptomatic
A = Asymptomatic B = Fever, night sweats or >10% weight loss
Describe the occurrence of B cell lymphomas
- Comprise over 90% of lymphoid neoplasms worldwide.
- This is why this is important
- Incidence rate per 100,000 is 26.13 and is increasing.
What types of B cell lymphoma originate from the germinal center of the lymph node?
- Follicular lymphoma
- Burkitt lymphoma