Lymphoma Flashcards
1
Q
What is a lymphoma and where can it arise? What are the two broad types of lymphoma?
A
- lymphoma is a neoplastic proliferation of lymphoid cells, resulting in the formation of a mass
- can arise in lymph nodes or in extra-nodal tissue (most tissues have some lymph tissue), so it can really arise anywhere
- 2 broad types: Hodgkin’s lymphoma (40%) and non-Hodgkin’s lymphoma (60%)
2
Q
What is the key cell involved in Hodgkin’s lymphoma? What markers does this cell have? Only a few of these cells are actually involved, so what causes the formation of a mass?
A
- Hodgkin’s lymphoma is characterized by the proliferation of Reed-Sternberg cells
- these are large B-cells with multi-lobed nuclei and prominent nucleoli (“owl eyed” nucleus); they classically express CD15 and CD30, but LACK CD20 (normally found on all B-cells)
- Reed-Sternberg cells actually release large amounts of cytokines, recruiting an accumulation of reactive cells; this is what forms the mass
- HL has 2 peaks of incidence: one occurring from 20-30 and another after 50
3
Q
What are the sub-types of Hodgkin lymphoma? What is a major feature of each?
A
- sub-types are based on the type(s) of reactive cells present in the lymphoma; there is the broad classification of classical (95%) vs. non-classical (5%)
- classical: nodular sclerosing, lymphocyte-rich, lymphocyte-mixed, and lymphocyte-depleted
- non-classical: AKA lymphocyte predominant
- nodular sclerosis (most common, 70% of HLs): classically arises in the neck or mediastinum in a young female; biopsy reveals broad bands of fibrosis and lacunar cells (the Reed-Sternberg cells lie in lacuna)
- lymphocyte-rich: has the best prognosis
- lymphocyte-mixed: poor prognosis; abundant eosinophils
- lymphocyte-depleted: has the worst prognosis; associated with elderly and HIV patients
- non-classical (lymphocyte predominant): no R-S cells (so no CD15 and CD30), popcorn cells
4
Q
Which cell type is usually involved in non-Hodgkin lymphoma? What are the major subtypes of NHL?
A
- most NHLs involve B-cells (80%)
- subtypes: DLBCL > follicular > mantle tied with SLL»_space; Burkitt
- follicular lymphoma, mantle cell lymphoma, and marginal zone lymphoma (these are all small cell NHLs)
- Burkitt lymphoma (this is an intermediate cell NHL)
- diffuse large B-cell lymphoma (this is a large cell NHL)
- (normal anatomy of lymph node: cortex with follicles surrounded by a mantle, which is further surrounded by a margin when the germinal center is active)
5
Q
What is follicular lymphoma? How does it present? What cytogenetic abnormality drives this lymphoma? What can follicular lymphoma progress to?
A
- follicular lymphoma is an indolent subtype of non-Hodgkin lymphoma (small cell type)
- it classically presents in late adulthood with painless generalized lymphadenopathy
- driven by t(14;18): 14’s Ig heavy chain translocates with 18’s BCL-2, resulting in over expression of Bcl-2; Bcl-2 stabilizes the mitochondrial membrane, thus the accumulation of Bcl-2 PREVENTS APOPTOSIS
- lack of apoptosis results in a lack of tingible body macrophages (vs. normal reactive follicle)
- can progress into the more aggressive diffuse large B-cell lymphoma
- this form of NHL is usually generalized with splenomegaly and marrow involvement, but extranodal disease is rare (compare to DLBCL)
6
Q
What distinguishes follicular lymphoma from benign follicular hyperplasia as seen infection?
A
- follicular lymphoma is characterized by:
- disruption of the normal architecture (follicles are seen in the paracortex and medulla)
- lack of tangible body macrophages in the germinal center (these are usually present to clear away the dead apoptotic cells, but in follicular lymphoma the cells don’t undergo apoptosis, so no macrophages are present)
- expression of Bcl-2
- monoclonality (vs. polyclonality in reactive hyperplasia, etc.)
7
Q
What is mantle cell lymphoma? How does it present? What cytogenetic abnormality drives this lymphoma?
A
- mantle cell lymphoma is an aggressive subtype of non-Hodgkin lymphoma (small cell type)
- it classically presents in late adulthood with painless generalized lymphadenopathy
- driven by t(11;14): 11’s cyclin D1 translocates with 14’s Ig heavy chain, resulting in over expression of cyclin D1; cyclin D1 allows progression from G1 to S in the cell cycle
8
Q
What is marginal zone lymphoma? What is it associated with?
A
- marginal zone lymphoma is an indolent subtype of non-Hodgkin lymphoma (small cell type)
- it is associated with chronic inflammatory states (such as Hashimoto’s thyroiditis, Sjogren syndrome, H. pylori gastritis)
9
Q
What is Burkitt lymphoma? What is it associated with and what cytogenetic abnormality drives this lymphoma? What characteristic finding do we see on histology? What are the two types?
A
- Burkitt lymphoma is a highly agressive intermediate cell subtype of non-Hodgkin lymphoma
- it is associated with EBV and is driven by a t(8;14) translocation; 8’s C-myc is translocated with 14’s IgH heavy chain, resulting in over expression of C-myc (an oncogene)
- it affects adolescents/young adults
- characteristic “starry sky” appearance on histo (sheets of lymphocytes with interspersed macrophages)
- African type: jaw lesion
- American type: pelvic/abdominal/GIT lesion
10
Q
What is diffuse large B-cell lymphoma? How can it arise?
A
- DLBCL is an aggressive subtype of non-Hodgkin lymphoma (large cell type)
- it is the MOST COMMON NHL
- can arise sporadically or from the transformation of follicular lymphoma and small lymphocytic lymphoma (CLL)
- it affects older adults (20% in children)
- this form of NHL is usually localized without splenomegaly or marrow involvement, but extranodal disease is common (compare to follicular lymphoma)
11
Q
What are the two non-Hodgkin lymphomas that involve T-cells?
A
- (20% of NHLs are of T-cell origin)
- adult T-cell lymphoma: caused by HTLV-1 (human T-cell lymphoptropic virus-1) in Japan and Caribbean
- mycosis fungoides and Sezary syndrome (leukemic phase of MF)
- (malignancies of T-cells tend to infiltrate the skin, causing cutaneous lesions/involvement)
