Lymphoma 1: MDT Flashcards
What is Lymphoma?
The term ‘lymphoma’ means a neoplastic (malignant) tumour of lymphoid cells.
Where are lymphomas usually found?
Lymphomas usually found in lymph nodes, bone marrow and/or blood (the lymphatic system) lymphoid organs; spleen or the gut-associated lymphoid tissue Skin (often T cell disease)
Rarely “anywhere” (breast kidney){*Immune privilege sites CNS, occular, testes}
What is the incidence of Lymphoma (Incl. HL and NHL)?
There are approximately 200 new cases per year for every million of the population (around 10,000 new cases a year in the UK).
Non-Hodgkin’s Lymphomas 80%
Hodgkin Lymphoma 20%
What are precursor malignancies?
Precursor cell neoplasia of B or T cell lineage:
Precursor B cell lymphoblastic leukaemia
Precursor T cell lymphoblastic leukaemia
What are mature B cell malignancies?
NHL
HL
What are mature T cell malignancies?
T cell or NK cell NHL
What are lymphoma RFs?
Most lymphoma subtypes/cases are sporadic with no known risk factors
Some lymphoma subtypes have specific risk factors immune diseases acquired or iatrogenic
Associated specific infections or inflammation
How does the limited instability of DNA become problematic in lymphoma?
- Lymphocytes undergo DNA changes in development:
Potential for recombination errors and new point mutations - Rapid cell proliferation in the germinal centre
Allows rapid response to infection
Rapid cell division = increased risk of DNA replication errors - Dependent on apoptosis
Exquisite antibody specificity & eliminates self reactive clones
Apoptosis is “switched off” in germinal centre
Consequences of mutation ins in apoptosis regulating genes
What is VDJ recombination?
Occurs in BM
Key enzymes: RAG1+2
TdT
What do B cells undergo?
Class switch recombination
Somatic hypermutation
Key enzyme: Adenosine induced Deaminase
What are immune gene recombination errors and lymphoma linked translocations?
Lymphoma/recombination associated translocations
Involves the Ig Locus (IgH, K or l loci)
Ig promoter highly active in B cells
Bring intact oncogenes close to the Ig promoter
Oncogenes may be anti apoptotic, proliferative.
bcl2
bcl6
Myc
cyclinD1
What are the 3 main groups of rare NHL subtypes?
- Constant antigenic stimulation- bacteria/ AI
- Viral infection (direct viral integration of lymphocytes)
- Loss of T cell function and EBV infection (B cell) - Loss of T cells (HIV), iatrogenic immunosuppression
What are the bacterial or AI driven causes of rare NHL (chronic inflammation)?
B cell Non Hodgkin Lymphoma Marginal zone sub type (MZL)
H.Pylori : Gastric MALT (mucosa associated lymphoid tissue) (MZL of stomach)
Sjogren syndrome : MZL of salivary glands
Hashimoto’s : MZL of thyroid
Enteropathy associated T-Cell
Non Hodgkin lymphoma (EATL)
Coeliac disease/Gluten: small intestine EATL
How does direct viral integration and lymphomagenesis occur?
HTLV1 retrovirus infects T cells by vertical transmission
Caribbean, Japan (and world wide) endemic infection
Risk of Adult T cell leukaemia lymphoma is 2.5% at 70 years
ATLL is a subtype of T cell Non Hodgkin Lymphoma
How does loss of T cell function occur?
HIV (in uncontrolled infection there is x60 increased incidence of B NHL )
Iatrogenic (transplant immunosuppression)
PTLD (post transplant lymphoproliferative disorder)
How does EBV infection result in lymphoma?
EBV infects B lymphocytes, healthy carrier state post glandular fever.
EBV driven proliferation of B cells is associated with surface expression of EBV antigens.
Proliferating B cells targeted and killed by EBV specific cytotoxic T cell response
How do CTLs cause EBV to cause havoc?
Loss of cytotoxic T cell function can cause failure to eliminate EBV driven proliferation of B cells
How do you make a haemato-oncology diagnosis?
Morphology (Cytology/ cytochemistry/ histo) Immunophenotye (Flow cytometry, immunohistochemistry) Cytogenetics (Conventional karyotyping, FISH) Molecular genetics (Sequencing, PCR, gene profiling, whole genome sequencing)
How many types of lymphoma are there?
> 60
How do we do diagnosis and staging?
Histological diagnosis
Anatomical stage (CT/ MRI/ PET/ BM biopsy)
Prognostic factors (LDH, beta2 mic, albumin, kidney or BM function)
What cells are specific to HL/ NLPHL?
Reed Sternberg cells
How many Lymphomas are HL?
15% (NHL = 85%)
What are the mature B and T cell lymphomas?
Mature B cell neoplasm
DLBCL, Follicular NHL, CLL etc
Mature T and NK neoplasm
PTCL, Anaplastic, Cutaneous
What is the epidemiology of HL?
1% of all cancer, 3:100,000 population
HL is more common in males than females.
Bimodal age incidence
Most common age 20-29, young women NS subtype
Second smaller peak affecting elderly >60 years old
What are the S/S of HL?
Painless enlargement of lymph node/nodes.
May cause obstructive symptoms/signs
Constitutional symptoms; fever, night sweats weight loss (the B symptoms) and pruritis may be present. Rarely alcohol induced pain
What is the classification of HLs?
Classical HL
Nodular sclerosing 80% Good prognosis (causes the peak incidence in young women)
Mixed cellularity 17% Good prognosis
Lymphocyte rich (rare) Good prognosis
Lymphocyte depleted (rare) Poor Prognosis
How common is NLPHL?
Nodular Lymphocyte predominant HL 5% (disorder of the elderly multiple recurrences)
How do you stage HL?
Following pathological diagnosis of a lymph node biopsy patients are ‘staged’ this has prognostic significance and also may determine the best approach for therapy.
FDG-PET/CT scan
Consider biopsy of other site if possibly infiltrated e.g. liver
What is the staging system?
Stage I; one group of nodes II; >1 group of nodes same side of the diaphragm III; nodes above and below the diaphragm IV; extra nodal spread Suffix A if none of below, B if any of below Fever Unexplained Weight loss >10% in 6 months Night sweats
How is chemo used?
Chemotherapy is often given as a combination of drugs which affect the malignant cells in different ways
Radiotherapy: HL is highly responsive to radiotherapy, can be given at end of chemo as an Involved field a small area only targeting diseased nodes (less toxicity to normal tissue)
Combined modality uses both chemo and radiotherapy
What is the chemo used for HL?
ABVD- 4 weekly intervals Adriamycin Bleomycin Vinblastine DTIC
Why is ABVD good?
Effective treatment
Preserves fertility (unlike MOPP the original chemo)
Can cause (long term):
Pulmonary fibrosis
cardiomyopathy
How is radiotherapy used for HL?
Modern practice involved field RT only
Low/negligible risk of relapse within field
Risk of damage to normal tissue:
- Ca breast (risk 1:4 after 25 years)
- Leukaemia/mds (3% at 10y)
- Lung or skin cancer
Combined modality greatest risk of second degree malignancy (two mechanisms of DNA damage)
What is the treatment for HL?
Chemotherapy required for all cases (ABVD)
ABVD 2-6 cycles (depending on stage) +/- Radiotherapy PET CT
Interim: post x2 cycles, response assessment
End of Treatment: Guides need for radiotherapy
Relapse
High dose salvage chemotherapy Autologous PB stem cell transplant as salvage
What is the outcome of therapy/ prognosis?
Outcome of therapy:
Older patients generally do less well as do those with lymphocyte-depleted histology.
Prognosis: This depends principally on stage. Cure rate ranges from 50-90%. Over 80% of patients with stage I or II disease are cured Only 50% of stage IV patients are cured
What are the treatment dilemmas?
HL is a curable disease overall approx 80%
10% die from relapse of HL (first 10 years)
10% die from treatment complications (after 10 years)
“Curing” cHL in a 25-year old woman using chemo plus radiotherapy does not guarantee long term survival!
What are the parts of the lymphoreticular system?
Generative LR tissue
Bone marrow and thymus
Function - generation/maturation of lymphoid cells
Reactive LR tissue
Lymph nodes and spleen
Function - development of immune reaction
Acquired LR tissue
Extranodal lymphoid tissue
E.g. Skin, stomach, lung
Function - development of local immune reaction
What are the cells of the lymphoreticular system?
B lymphocytes
Express surface immunoglobulin
Antibody production
T lymphocytes
Express surface T cell receptor
Regulation of B cell and macrophage function
Cytotoxic function
Antigen presenting cells
Macrophages
Connective tissue cells
Where do B cells bind to antigen epitopes?
Germinal center (B cells, Antigen presenting cells)
This is where B cells which bind antigen epitopes are selected and activated
What is the T cell area?
Comprises
T cells
Antigen presenting cells
High endothelial vessels
This is where T cells which bind antigen epitopes are selected and activated
How do we identify different types of lymphocytes?
Identify lymphocyte subtypes and different stages of development by the different types of cell surface receptors expressed by the cells
These are called CD markers - over 100!
They can be detected in tissue samples using immunohistochemistry
What is the site of lyphoma?
Arise in and involve lymphoid tissues (including acquired lymphoid tissue - extranodal lymphomas)
What is the pathogenesis of lymphoma (clonal neoplasia)?
Mutation in genes to allow uncontrolled cell growth
Normal lymphocytes undergo controlled genomic “instability” of lymphoid cells - mistakes in this process produce neoplastic mutations
Inherited disorders – inherited disorder resulting in increased/abnormal genomic instability
Viral agents – EBV, HTLV-1
Environmental agents – mutagens, chronic immune stimulation (e.g H pylori)
Iatrogenic causes – radiotherapy, chemotherapy
ALSO immunosuppression (infection + loss of surveillance)
What is the WHO classification of lymphoma?
HODGKIN LYMPHOMA
Classical
Lymphocyte predominant
NON-HODGKIN LYMPHOMA B cell Precursor B cell neoplasms Peripheral B cell neoplasms Low grade High grade T cell Precursor T cell neoplasms Peripheral T cell neoplasms
What are the basic principles of lymphoma?
B cell Non-Hodgkin lymphomas most common type (80-85 %)
Can arise at different stages of lymphocyte development and activation
Therefore in certain lymphomas the neoplastic lymphoid cell resembles a normal counterpoint both in morphology and in the pattern of CD markers expressed.
Neoplastic lymphoid cells circulate in blood
Hence often disseminated at presentation (although this may be sub-microscopic). Exception is Hodgkin lymphoma and some very early NHL
Lymphoid neoplasms may disrupt normal immune system
Therefore patients may develop immunodeficiencies
What are diagnostic tools pathologists can use?
Morphology
Cytology: Look at single cells aspirated from a lump
Histology: look at tissue sections Architecture Nodular Diffuse Cells Small round Small cleaved Large (centroblastic, immunoblastic, plasmablastic)
How is immunohistochemistry used?
Used to identify proteins on/in cells in tissue sections
Use labelled antibody to cell surface receptor
Dye label is visible under light microscope in tissue sections
How can we differentiate cell types with immuno?
T = CD3, CD5 B = CD20
What can you see on immunophenotyping?
Cell type
Cell distribution
Loss of normal surface proteins E.g. neoplastic T cells
Abnormal expression of proteins (often secondary to specific chromosomal/ gene abnormalities) E.g Cyclin D1
Clonality of B cells
Light chain expression
Which molecular tools are available?
FISH (chromosome translocations) e.g. anaplastic large cell lymphoma t(2:5)
PCR (translocations, clonal TCR or Ig gene rearrangement)
What can be used in PCR for diagnosis and prognosis?
Diagnostic
E.g 11;14 Mantle cell lymphoma
Prognostic
E.g. 2;5 Anaplastic large cell lymphoma
What are common B cell NHL lymphomas?
Low grade
Follicular lymphoma
CLL (Small lymphocytic lymphoma/chronic lymphocytic leukaemia)
Marginal zone lymphoma
High grade
Diffuse large B cell lymphoma
Intermediate
Burkitt’s lymphoma
Aggressive
Mantle cell lymphoma (disseminated at presentations)
What is follicular lymphoma?
Clinical: Lymphadenopathy. MA/elderly
Histopathology: Follicular pattern, Germinal centre cell origin CD10, bcl6+
Molecular: t(14;18) - bcl-2 gene
Indolent but can transform to high grade lymphoma
What would immunohistochemistry show in follicular lymphoma?
Detection of bcl-2 expression by neoplastic B cells in follicles
What is CLL (small lymphocytic lymphoma)?
Clinical: MA/elderly; nodes or blood
Histopathology: Small lymphocytes, Naïve or post-germinal centre memory B cell, CD5, CD23 +
Molecular,: Multiple genetic abnormalities
Indolent, but can transform to high grade lymphoma (Richter transformation)
What is MALT lymphoma?
Arise mainly at extranodal sites (many sites, e.g. gut, lung, spleen)
Thought to arise in response to chronic antigen stimulation (e.g. by Helicobacter in stomach)
Post germinal centre memory B cell
Indolent but can transform to high grade lymphoma
Can treat low grade disease with non-chemotheraputic modalities - i.e. remove antigen E.g Helicobacter eradication
What is mantle cell lymphoma?
Clinical: MA male predominence, Lymph nodes, GI tract, Disseminated disease at presentation, Med survival 3-5 years
Histopathology: Located in mantle zone, Pre-germinal centre cell, Aberrant CD5, cyclin D1 expression
Molecular: t(11;14)- Cyclin D1 over expression
AGGRESSIVE: Median SR 3-5 yrs
What is Burkitt’s Lymphoma?
Clinical: Jaw or abdominal mass children/young adults
Types: Endemic (children/ YA), (Adults) Sporadic, Immunodeficiency, EBV associated
Histopathology: Germinal center cell origin, “starry-sky” appearance
Molecular: t(8:14, 2:8, 8;22) - C-myc
Aggressive disease
What is the presentation/ pathology of Diffuse large B cell lymphoma?
Clinical: MA/elderly, Lymphadenopathy
Histopathology: Germinal center or post-germinal center B cell, Sheets of large lymphoid cells,
Germinal center phenotype = good prognosis
p53 positive, high proliferation fraction = poor prognosis
What are T cell lymphomas?
Rarer NHLs - Peripheral T cell lymphoma NOS
Clinical: MA/elderly, Lymphadenopathy and extranodal sites
Hist/cyto: Large T lymphocytes, Often with associated reactive cell population, esp eosinophils
Aggressive
What are special forms of T cell lymphoma?
Adult T cell leukaemia/lymphoma
Caribbean and Japan
Associated with HTLV-1 infection
Enteropathy associated T cell lymphoma
Some patients with long standing coeliac disease
Cutaneous T cell lymphomas E.g. mycosis fungoides - more indolent
Anaplastic large cell lymphoma
What is anaplastic large cell lymphoma?
Clinical: Children/young adults, Lymphadenopathy
Histopathology: Large “epithelioid” lymphocytes, T cell or null phenotype
Molecular
t(2;5) - Alk-1 protein expression
Aggressive
Alk-1 positive better prognosis
CD30 positive
Summarise HL and NHL
Hodgkin Lymphoma
More often localised to a single nodal sit
Spreads contiguously to adjacent lymph nodes
Non-Hodgkin Lymphoma
More often involves multiple lymph node sites
Spreads discontinuously
What is the difference between classical HL and NLPHL?
Classical Several subtypes Nodular sclerosing Mixed cellularity Lymphocyte rich and lymphocyte depleted
Lymphocyte predominent
Some relationship to non-Hodgkin’s lymphoma
What is the presentation of classical lymphoma?
Clinical: Young and MA, Often involves just single lymph node group, EBV associated
Staining: Thought to be germinal center/post germinal center B cell origin, CD30+, CD15+, CD20-
Histopathology: Sclerosis, mixed cell population in which scattered Reed-Sternberg and Hodgkin cells with eosinophils
Moderately aggressive
What is the presentation of NLPHL?
Clinical: Isolated lymphadenopathy, Germinal centre B cell (positive for some germinal centre B cell markers), No association with EBV
Markers: CD20, CD30-, CD15-
Histopathology: B cell rich nodules with scattered L&H cells, Indolent
Can transform to high grade B cell lymphoma
Which of these is common: CLL, myeloma, hairy cell leukaemia
CLL and myeloma
How do lymphocytes uphold DNA instability normally?
DNA molecules are 1) cut and recombined 2) subjected to deliberate DNA mutagenesis (somatic hypermutation)
Generates immunoglobulin and T cell receptor diversity and Ig class switching
How many lymphocytes die in the germinal centre?
(90% of normal lymphocytes die in the Germinal centre!)
Give an example of a translocation that may cause cancer in B cells
t(8:14) - c-myc oncogene for Ig molecules- proto-oncogene and oncogenesis
What happens in the lymphoid follicle?
Mantle zone
Naïve unstimulated B cells
Germinal center
B cells
Antigen presenting cells
This is where B cells which bind antigen epitopes are selected and activated
What does starry sky represent in Burkitt’s lymphoma?
Stars- Macrophages which are full of debris
Sky- Tightly packed little cytoplasm lymphoma cells
