Week 10 Part 2 - FNA Lymph Node Cytopathology Flashcards
Low Grade, Scattered Large Cell and High Grade Lymphoma Examples
Low grade lymphoma
- monotonous small cell pattern
- mixed cell pattern
Scattered large cell pattern
- Hodgkin lymphoma
- some NHL
High grade lymphoma
- large malignant cell pattern
- blastic/Burkitt pattern
What to Look for in Flow Cytometry for Lymphoma Classification
CD45+ Lymphocytes
CD19+ B cells + CD3+ T cells
(Check T cell populations- CD4, CD8, loss of other T markers)
Look for CD20-/weak, CD10+ and CD5+ B cells
Check Kappa + Lambda = B cells
Look for B cell clonality
Abnormal Flow Findings in Lymphoma
Light chain restricted B cell population
Surface and cytoplasmic negative population (>20% of B cells)
Aberrant T cell population (e.g. loss of pan-T markers, abnormal ratios)
Strengths of Flow Cytometry in Lymphoma Analysis
Separation of low grade lymphomas from benign nodes
Limitations of Flow Cytometry in Lymphoma Analysis
Hodgkin Lymphoma
T cell lymphoma
Some B cell lymphoma- fragile large cells, light chain negative
False positives in solid organs (e.g. thyroid)
Thymic lymphoid populations
Low Grade Lymphoma - Monotonous Small Cell Pattern Differential Diagnosis
Quiescent/benign lymph node
CLL/SLL
Mantle cell lymphoma
Lymphoplasmacytic lymphoma
Chronic/Small Lymphocytic Leukaemia (CLL/SLL) - Clincal
Largely a disease of older adults (i.e. very rare before age 40)
Usually have nodal, peripheral blood, bone marrow and splenic involvement
Clinical course is relatively indolent in most cases
Often receive no or mild treatment
10-20% develop Richter’s Syndrome
CLL/SLL Cytology
Small round lymphoid cells with clumped chromatin
Population of slightly larger cells with vesicular chromatin and nucleoli
Generally less nuclear irregularity than MCL
CLL/SLL IHC
CD5+, CD19+, CD23+, weak CD20, CycD1-
Mantle Cell Lymphoma Cytology
Monotonous population of small lymphocytes
Population of large cells with slight but distinctive nuclear irregularity
Mantle Cell IHC
CD5+, CD20+ (bright) CycD1+, CD23-
Also has t(11:14) chromosomal abnormality
Comparison of SLL and MCL
SLL
- round
- smooth
- prolymphocytes
- CD23+, CD20 dim
MCL
- irregular
- more monotonous
- histiocytes
- CD23-, CD20 bright
Scattered Large Cell Pattern Lymphoma
Hodgkin lymphoma
T cell rich B cell lymphoma
Non-haematopoietic tumours
Need cell block
Flow not useful in HL
Need histological conformation
Hodgkin Lymphoma
Usually arises in lymph nodes, preferentially cervical
Small numbers of neoplastic cells in a variable reactive background
Hodgkin Lymphoma Cytology
Reed-Sternberg cells
Atypical mononuclear cells (‘Hodgkin cell)
BG eosinophils, plasma cells and histiocytes
Lymphocytes dispersed within the background
Nodular Lymphocyte Predominant HL (NLPHL)
Relatively uncommon (5% of HL)
The histological description is of “popcorn cells” with a background of lymphocytes
Immunophenotype is that of B cells:
- CD45 and CD20 pos
- CD15 and CD30 neg
Small cells are a mixture of B cells and CD4+ Th cells
Low Grade Lymphoma - Mixed Cell Pattern Lymphoma Differential Diagnosis
Reactive lymph node
Follicular lymphoma
CLL/SLL with prominent proliferation centres
Marginal zone lymphoma
Tricky large cell pattern cases
T cell lymphoma
What does a Reactive Background Contain?
Lymphocytes
Eosinophils
Histiocytes
Follicular Lymphoma
Common, usually indolent lymphoma of elderly
Grading based on number of centroblasts:
- Grade 1: 0-5 centroblasts/HPF
- Grade 2: 6-15 centroblasts/HPF
- Grade 3a: > 15 centroblasts but centrocytes are still present
- Grade 3b: centroblasts form solid sheets with no residual centrocytes
Tendency to progress in grade, develop diffuse growth
t(14:18) translocation
Shows follicular pattern on cytology
Follicular Lymphoma IHC
Positive: CD10, CD20, >MUM1 expression (75%) and >Ki-67 proliferation rate
Negative CD5, Cyclin D1
Examples of Large Cell Lymphomas
Diffuse large B cell lymphoma
Grade 3 follicular lymphoma
T cell lymphoma
Generally not a diagnostic challenge to recognise as malignant
Flow cytometry of limited value
Cell block critical
Diffuse Large B Cell and High Grade Follicular Lymphoma
DLBCL and grade 3b FL are similar on FNA
There is overlap in immunophenotype and genetics
DLBCL
- may be centroblastic, immunoblastic or anaplastic in type
- is characterised by the immunophenotype CD5+ large B cell lymphoma
- T cell rich large B cell lymphoma is clinicopathologically a distinct type of DLBCL
Diffuse Large B Cell and High Grade Follicular Lymphoma Cytology Comparison
FL - High grade monotonous population of large lymphocytes with nuclear abnormality and prominent nucleoli
DLBCL - with large cells showing plasmacytoid diff
Blastoid Lymphomas
Medium size cells, 1-3 nucleoli
Vacuolated cytoplasm makes it easy to identify
Features of proliferation
- mitoses
- TBMs
- Ki67>90%
Need:
- flow
- cell block- Ki67, TdT, cyclin D1
- FISH
