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PATH FINAL > Haem: Lymphoma > Flashcards

Haem: Lymphoma Flashcards

1
Q

Define lymphoma

A

Neoplastic tumour of lymphoid tissue

Often involving:
Lymph nodes +/- bone marrow
- at times other lymphoid tissues (spleen, MALT)

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2
Q

Outline the aetiology for lymphomas

A

Acquired somatic mutations
- sporadic in nature (most cases - and this occurs due to adaptive immune system’s DNA instability in order to achieve its diversity)
- arising from immune disease
- associated with specific infections

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3
Q

Outline how the processes by which immunoglobulins and T cell receptors become capable of identifying a wide variety of antigens increases the risk of lymphoma.

A
  • DNA recombination (VDJ gene and somatic hypermutation) - increase risk of point mutations and fusion genes (may place intact oncogenes next to the Ig gene promoter which is extremely active - hence increasing expression of oncogene)
  • Rapid cell turnover - increases risk of DNA repitition errors. If a mutation turns off apoptosis (lymphocytes are heavily reliant on apoptosis to control auto-reactive cells) increases risk of malignancy and/or autoimmunity.
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4
Q

What are the specific risk factors that predispose someone to develop certain types of lymphoma

A
  • Constant antigenic stimulation (chronic bacterial or autoimmune disease)
  • Viral infection (direct viral integration in lymphocyte)
  • Loss of T cell function in those co-infected with EBV
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5
Q

Explain which types of lymphoma can arise from constant antigenic stimulation can lead to lymphoma.

A
  • H. pylori → gastric MALT marginal zone NHL of the stomach
  • Sjogren syndrome → marginal zone NHL of the parotid
  • Hashimoto → marginal zone NHL of thyroid
  • Coeliac disease → small bowel T cell lymphoma: enteropathy-associated T cell NHL
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6
Q

List an example of a viral infection that can lead to a lymphoma.

A

Direct viral integration: HTLV1

  • HTLV1 infects T cells by vertical transmission
  • May cause adult T cell leukaemia/lymphoma (very aggressive)
  • Caused by viral genome integrating into T cell genome and driving proliferation
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7
Q

Explain how the loss of T cell function in those co-infected with EBV can result in a lymphoma

A

EBV infection and immunosuppression

  • EBV established latent infection in B cells which is kept in check by cytotoxic T cell (kill EBV antigen-expressing B cells)
  • Loss of T cell function (e.g. HIV, post-transplant immunosuppression) causes the cytotoxic T cells from being unable to keep proliferative EBV-infected B cells in check and tehrefore result in a EBV-driven B cell lymphoma
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8
Q

List some different types of tissues of the lymphoreticular system.

A
  • Generative tissue: bone marrow and thymus (generates or matures lymphoid cells)
  • Reactive tissue: lymph nodes and spleen (development of immune reaction)
  • Acquired tissue: extra-nodal lymphoid tissue (e.g. skin, stomach, lung - responsible for developing a local immune response)
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9
Q

List the different cell types of the lymphoreticular system.

A

Lymphocytes:
* B cells
* T cells

Accessory cells:
* Antigen-presenting cells
* Macrophages
* Connective tissue cells

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10
Q

Describe the normal histological appearance of a lymph node.

A

Composed of rounded areas full of B cells (B cell follicles)
* The mantle zone is a crescent-shaped region where naïve unstimulated B cells are found
* These naïve B cells will eventually migrate into the germinal centre (lighter circle),
* In the germinal centre, B cells will be exposed to APC which can result in them being maturing and becoming antibody producing plasma cell OR becoming marginal zone B cells and leaving germinal centre.

T cells are found in T cell areas surrounding the B cell follicles. Filled with APCs and high-endothelial venules.

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11
Q

What is the main technique used to identify different types of lymphocytes within a lymph node biopsy?

A

Immunohistochemistry

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12
Q

What are the main markers used for B and T cells?

A

T cell = CD3, CD4, CD5, CD8

B cell = CD19, CD20, CD22

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13
Q

Define lymphoma.

A
  • Neoplastic proliferation of lymphoid cells forming discrete tissue masses
  • They arise in and involve lymphoid tissues
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14
Q

Which pathology tools can be performed to classify a lymphoma?

A
  • Cytology (looking at single cell shape and size, nuclei)
    • larger cells = high grade B cell lymphoma
  • Histology (assessing architecture and cellular arrangement)
    • diffuse arrangement = CLL/small lymphocytic lymphoma
    • small cleaved cells = mantle lymphoma, follicular lymphoma
    • large cells with large nuclei = high grade diffuse lymphoma
  • Immunohistochemistry (allows CD markers to differentiate between T and B cell)
    * allows further differentiation of germinal centre vs post-germinal centre B cell lymphomas
  • Molecular tools
    • FISH/PCR for chromosomal translocations
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15
Q

Outline the WHO classification of lymphoma.

A

Hodgkin lymphoma (20%)

  • Classical
  • Non-Classic Lymphocyte predominant

Non-Hodgkin lymphoma (80%)

  • B cell (MOST COMMON)
    • Precursor B cell neoplasm
    • Peripheral B cell neoplasm (low and high grade)
  • T cell
    • Precursor T cell neoplasm
    • Peripheral T cell neoplasm
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16
Q

Why is non-Hodgkin lymphoma often disseminated at presentation?

A

Neoplastic NHL lymphoid cells circulate in the blood rathertahn lymph leading to disseminated disease at presentation

NOTE: lymphoid neoplasms can disrupt normal immune functioning leading to immunodeficiencies

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17
Q

Histology grading system for B cell Lymphomas

A

Lower grade (small lymphocytes)
* Follicular lymphoma
* Small lymphocytic lymphoma (CLL)
* Marginal zone lymphoma

High Grade (large lymphocytes)
* Aggressive = Diffuse Large B-cell + Mantle cell lymphoma (histologically looks similiar to lower grade)
* Very Aggressive = Burkitt’s (fastest developing cancer in humans)

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18
Q

Describe the histological features of follilcular lymphoma.

A
  • Follicular pattern in the lymph nodes - the follicles are neoplastic (there are loads of them in the lymph node) and spread from the node into adjacent tissues
  • “Nodular appearance”
  • Cells have a germinal centre cell origin (hence positive staining for CD10)
  • Also Bcl6 +ve due to translocation (14;18)
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19
Q

Which molecular feature (translocation) is associated with follicular lymphoma? and what protoncogene is overexpressed

A

14;18 translocation = Bcl2 gene

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20
Q

Outline the histological features of small lymphocyte lymphoma.

A
  • Small lymphocytes
  • Arise from naïve B cells or post-germinal centre memory B cells
  • Cells are CD5 and CD23 positivie (these +ve results are only seen in B cells if they are neoplastic!)
  • They replace the entire lymph node so that you can no longer identify follicles or T cell areas
21
Q

What is the term used to describe the transformation of small lymphocytic lymphoma into a higher grade lymphoma/leukaemia?

A

Richter transformation

22
Q

What is marginal zone lymphoma?

A
  • Arise mainly in extra-nodal sites (e.g. gut, spleen)
  • Thought to arise due to chronic antigenic stimulation
  • Arise from post-germinal centre memory B cells
  • Low-grade disease can be treated by non-chemotherapeutic methods (e.g. H. pylori eradication)
23
Q

Outline the typical demographic of patients with mantle cell lymphoma.

A
  • Typically affects middle-aged males

NOTE: median survival = 3-5 years

24
Q

Outline the key histological features of mantle cell lymphoma.

A
  • Located in the mantle zone of the lymph node
  • Arise from pre-germinal centre cells
  • Show aberrant expression of cyclin D1 and CD5
    cyclin D1 +ve = confirms diagnosis
25
Q

Which molecular features are characteristic of mantle cell lymphoma?

A
  • 11;14 translocation
  • Cyclin D1 overexpression
26
Q

Outline the typical presentation of Burkitt’s lymphoma.

A
  • Jaw or abdominal mass in children and young adults
  • Associated with EBV

NOTE: this is very agressive

27
Q

Outline the histological features of Burkitt’s lymphoma.

A
  • Arises from germinal centre cells
  • Starry sky appearance of sheets of medium sized lymphoma with small nuclei with macrophages filled with cellular debris
  • c-Myc +ve
28
Q

Outline the different types of Burkitt’s Lymphoma

A

Endemic
- most common malignancy in equitoral Africa
- EBV-associated
- Characteristic jaw involvement and abdominal masses

Sporadic
- EBV associated
- Jaw less commonly involved

Immuno-deficiency
- HIV/Post transplant patients
- EBV-associated

29
Q

Which molecular feature is associated with Burkitt’s lymphoma.

A
  • c-Myc translocation (8;14, 2;8 or 8;22)
30
Q

Outline the histological features of diffuse large B cell lymphoma.

A
  • Arise from germinal centre (CD10+) or pre-germinal centre B cells
  • Large lymphoid cells
  • Lymph node is effaced so follicles and germinal centres cannot be identified - described as “sheets of large lymphoid cells with variable shaped nuclei”
31
Q

List some prognostic association of diffuse large B cell lymphoma.

A

Good prognosis - germinal centre phenotype

32
Q

Outline some key histological features of T cell lymphomas.

A
  • Large T lymphocytes
  • Associated reactive cell population in histology (especially eosinophils)
33
Q

List some types of T cell lymphoma and their associations.

A
  • Adult T cell leukaemia/lymphoma - HTLV1 (CD4+ve)
  • Enteropathy-associated T cell lymphoma - Coeliac disease
  • Cutaneous T cell lymphoma (mycosis fungoides)
  • Anaplastic large cell lymphoma - t(2;5)
34
Q

Outline the typical demographics of anaplastic large cell lymphoma.

A

Children and young adults with lymphadenopathy

NOTE: this is aggressive

35
Q

Outline the key histological features of anaplastic large T cell lymphoma.

A
  • Large epithelioid lymphocytes
  • T cell (CD3 +ve) or null phenotype (anaplastic - CD3 -ve cells, all other CD markers negative too)
36
Q

Which molecular features are associated with anaplastic large cell lymphoma?

A
  • 2;5 translocation
  • Alk-1 protein expression - (used for diagnosis)
37
Q

Outline the key histological features of Enteropathy-associated T cell lymphoma

A

Intraepithelial CD8 +ve T cells mainly in small bowel causing solid tumours.

38
Q

Outline the key histological features of cutaneous T cell lymphoma

A

CD4+ve in epidermis and dermis
Causes tumours and nodules in skin.

39
Q

List some key differences between Hodgkin and Non-Hodgkin Lymphoma.

A
  • Hodgkin is more localised (usually one nodal site)
  • Hodgkin spreads contiguously to adjacent to adjacent lymph nodes
40
Q

Types of Hodgkins Lymphoma

A

Classic Hodgkins Lymphoma

Non-classic Lymphocyte predominant Hodgkins Lymphoma

41
Q

Outline the typical presentation of classical Hodgkin lymphoma.

A
  • Young and middle-aged patients with only a single group of lymph nodes involved
  • Associated with EBV
42
Q

Outline some histological features of classical Hodgkin lymphoma.

A
  • Nodular sclerosis
  • Lymphoma infiltrate composes of a mixed cellular population (eosinophils, macrophages) with some neoplastic lymphocytes scattered around (Reed-Sternberg cells). - this is unlike NHL lymphomas!
  • Reed sternberg cells (lymphocytes with large prominent nuclei surrounding a darker nulei - often binuclear)
  • Neoplastic cells are CD20-ve but CD15+ve and CD30+ve
43
Q

What are the diagnostic CD markers for Hodgkin lymphoma?

A
  • CD15
  • CD30

Negative for CD20!

44
Q

Outline the key histological features of lymphocyte predominant Hodgkin lymphoma.

A
  • Tumor is composed of few neoplastic Reed-Sternberg cell variants, also known as “popcorn” cells, in a background of non-neoplastic small lymphocytes
  • But unlike classic = CD20+ve, CD15 -ve, CD30 -ve
  • Neoplastic cells are germinal centre B cell (hence CD10+ve and Bcl 6+ve)
45
Q

Which markers are key in the diagnosis of lymphocyte predominant Hodgkin lymphoma?

A
  • Positive = CD20
  • Negative = CD15, CD30 (unlike classical Hodgkin lymphoma)
46
Q

Translocation associated with Burkitt’s Lymphoma

A

t(8;14) = c-myc oncogene overexpression

47
Q

Translocation associated with Mantle cell lymphoma

A

t(11;14) = cyclinD1 deregulation

48
Q

Translocation associated with Follicular Lymphoma

A

t(14;18) = bcl2

49
Q

Translocation associated with Anaplastic large cell lymphoma

A

t(2;5) = Alk1 overexpression

PATH FINAL (36 decks)

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