Haem: Lymphomas 1 - Multidisciplinary Flashcards
What is lymphoma?
tumour of lymphoid cells
What are the 2 types of lymphomas and which is more common?
80%= Non-Hodgkin’s 20%= Hodgkin’s
What are the 2 other ways of classifying lymphoid malignancies?
T or B cell (myeloid) lineage
Have precursor haematopoietic malignancies or Have mature lymphoid malignancies
What are the 3 reasons lymphocytes have such a high risk of developing maligancies?
1- Go through several point mutations that there is a high potential for recombination errors
2- Hyperproliferation so higher chances of DNA replication error
3- Rely on apoptosis. If mutation turns off apoptosis - DANGER
What happens in somatic hypermutation?
VDJ recombination - Class switching (from IgM to IgG/IgA)
How is there an over-expression of oncogenes in lymphomas?
A B cell that is tuned to respond to antibody will have a highly active immunoglobulin promoter (which sits upstream of the rearranged immunoglobulin molecule), with the purpose of driving antibody production.
However, if there has been a recombination error (e.g. when switching from IgM to IgG), the DNA being translocated and recombined may have pro-oncogenic potential.
These cell-promoting oncogenes can get translocated (due to error) downstream from the immunoglobulin promoter.
What are 3 risk factors for lymphoma?
Constant antigenic stimulation - Due to infections or autoimmune diseases
Viral infections
Loss of T cell fx - HIV killing T cells or Iatrogenic immunosuppresion
(Lose the sureveillance effect of cytotoxic T cells)
What are some examples of chronic antigen stimulation?
B cell Non-Hodgkin’s Lymphoma- Marginal Zone Subtype (MZL)
- H pylori Gastric MALT - Sjogren's - MZL of parotid - Hashimoto's - MZL of thyroid
Enteropathy associated T-cell Non-Hodgkin’s lymphoma (EATL)
- Due to coeliac
How does HTLV1 affect T cells and how can it present?
Vertical transmission and after a lifetime of carrying it, they can present neurologically as Tropical Spastic Paraparesis
What kind of T cell lymphomas can HTLV1 cause and how does it present?
ATLL - lymphadenopathy, hepatosplenomegaly, skin lesions + hypercalcaemia
What are the 2 ways in which viral infections can give rise to post-transplant or immunosuppression-associated B cell lymphomas?
EBV- drives B cell proliferation
HIV- leads to loss of T cell function (or loss of function via steroids, immunosuppression etc.)
What happens in Iatrogenic (transplant immunosuppression)- Post-transplant lymphoproliferative disorder?
Loss of T cell function
What are the 3 lymphoreticular tissues?
Generative lymphoreticular tissue
Reactive lymphoreticular tissue
Acquired lymphoreticular tissue
What are the 2 types of cells in the lymphoreticular system?
Lymphocytes - T and B cells
Accessory cells - Antigen presenting cells
Explain where and how B cells mature?
They mature in the bone marrow.
Naive B cells enter the lymph nodes and reside in the mantle zone. They then enter the germinal centre where their maturation and proliferation begins. This is where most things can go wrong.
What are the 2 types of cells B cells can grow into?
Antibody secreting plasma cells
Memory B cells
Where do T cells develop and what are the 2 types they can develop into?
Thymus
CD8+ cytotoxic cells
CD4+ helper cells
What are the main cell markers expressed by B cells?
CD20
What are the main cell markers expressed by T cells?
CD2, CD3 and CD5
What are the main cell markers expressed by early lymphocytes developing in the bone marrow?
CD 34 and TDT
What are the main cell markers expressed by lymphocytes in the germinal / follicular centres of lymph nodes?
CD10 and BCL-6
Why does immunosuppression increase the risk of lymphomas?
Predisposed to infection
Loss of surveillance of cell replication
What are the 2 ways of classifying lymphomas
Hodgkins and non Hodgkin
What are the 2 ways of classifying Hodgkins
Classical
Lymphocyte predominant
What are the 2 ways of classifying non - Hodgkins
T cell
- Precursor T cell neoplasm
- Mature/ Peripheral T cell neoplasm
B Cell
- Precursor B cell neoplasm
- Mature/ Peripheral B cell neoplasm - Low or high grade
Why does Non Hodgkins tend to not be disseminated?
As it affects only one or two lymph nodes
Which cells give rise to CLL
Naive B cells
What is multiple myeloma?
Sheets of cells that resemble normal plasma cells and secrete abnormal amounts of antibodies
When looking at tissue architecture, if it is nodular, what type of lymphoma could it be?
Follicular
When looking at tissue architecture, if it is diffuse, what type of lymphoma could it be?
CLL
When looking at tissue cells, if it is small and round, what grade of lymphoma could it be?
Low
If round, small and uniform - CLL
When looking at tissue cells, if it is small and cleaved, what type of lymphoma could it be?
Mantle cell or follicular
When looking at tissue cells, if it is large, what grade of lymphoma could it be?
High
When looking at tissue cells, if it is large with large nuclei and prominent nucleoli, what type of lymphoma could it be?
Burkitt’s
Diffuse B cell