Non-Hodgkin lymphoma pathophysiology
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Preeti Singh, M.B.B.S.[2]
Overview
Non Hodgkin's Lymphoma (NHL) represents a heterogeneous group of diseases with varied clinical presentation and histological appearance.It arises from cell of the lymphoid system, tumors are mainly derived from B lymphocytes, but are also from T lymphocytes, or natural killer cells. Lymphomas rise from different stages of B and T cell differentiation. Aberrations in the tightly controlled steps of B cell development can lead to oncogenesis. These aberrations are mainly seen in form of chromosomal translocation. About 85% of NHL's are of B-cell origin and only 15% are derived from T/NK cells. Two specific lymphomas, follicular lymphoma and diffuse large B cell lymphoma, account for about 65% of all non-Hodgkin lymphomas.
Pathophysiology
- Lymphomas can arise from different stages of B cell development:
- B cell development starts in the primary lymphoid tissue, the bone marrow and subsequent maturation takes place in secondary lymphoid tissue (spleen and lymph nodes).
- At the germinal centers of secondary lymphoid tissue B cells encounter antigens via T cells and then undergo affinity maturation to produce immunoglobulins of high affinity.
- It supports rapid B-cell proliferation for immunoglobulin affinity maturation and production of antibody diversity through two processes know as somatic hypermutation (SHM) and immunoglobulin class switching.
- Both of these processes require rapid cell turnover and multiple double stranded DNA breaks, which is error-prone.
- Somatically acquired genetic alterations ( mainly translocations) of these processes is probably the underlying cause of lymphomagenesis.
- The major subtypes of non-hodgkin lymphoma (NHL) include the following:
- Mature B-cell neoplasms:
- Diffuse large B cell lymphoma
- Follicular lymphoma
- Burkitt lymphoma
- Mantle cell lymphoma
- Hairy cell leukemia
- Extranodal marginal zone lymphoma
- Splenic marginal zone lymphoma
- Plasma cell myeloma
- Mature T and NK neoplasms:
- Mature B-cell neoplasms:
- About 85% of NHLs are of B-cell origin and only 15% are derived from T/NK cells.[1]
- The small remainder stem from macrophages.
- These tumors are characterized by the level of differentiation, the size of the cell of origin, the origin cell's rate of proliferation, and the histologic pattern of growth.
- Lymphomas of small lymphocytes generally have a more indolent course than those of large lymphocytes, which may have intermediate-grade or high-grade aggressiveness.
- Two specific lymphomas, follicular lymphoma and Diffuse Large B Cell Lymphoma, account for about 65% of all non-Hodgkin lymphomas.
- The gene-expression profiles of almost all non-Hodgkin lymphomas are a reflection of the equivalent healthy cell of origin from which the lymphoma is derived.[1]
- Follicular lymphoma most commonly results from the t(14;18)(q32;q21) translocation; this translocation places BCL2 (which encodes B-cell CLL/lymphoma 2) under control of the IGH enhancer element, leading to constitutive BCL2 expression.[2]
- BCL-2 is an anti-apoptotic protein, and the t(14;18)(q32;q21) translocation results in markedly elevated expression of BCL-2, which blocks the healthy germinal center default programme of apoptotic cell death and represents a defi ning pathogenic feature of follicular lymphoma.[2][3]
- Similarly, mantle cell lymphoma is characterised by the t(11;14)(q13;q32) translocation, which leads to the deregulated expression of cyclin D1.[4]
- Moreover, Burkitt lymphoma overexpresses MYC as a result of the t(8;14)(q24;q32) translocation or variants.
- Recurrent translocations are less common in peripheral T-cell lymphomas than in other types of lymphoma, and examples include the characteristic t(2;5) (p23;q35) translocation seen in anaplastic lymphoma kinase (ALK)-positive anaplastic T-cell lymphoma and the t(5;9)(q33;q22) translocation associated with follicular T-cell lymphoma.[5]
- Recurrent translocations including t(6;7) (p25;q32) and recurrent gene fusions involving the tumour-suppressor gene TP63 are characteristic of ALK-negative anaplastic T-cell lymphoma.[5][6]
Genetics
The development of Non-Hodgkin lymphoma is the result of multiple genetic mutations such as:[7][8]
- Mutations of the B-cell receptor genes and NFKB pathway
- RNA splicing mutations in the small lymphocytic lymphoma
- Genetic mutations in histone formation:[9]
- MLL2
- MEF2B
- EZH2
- CREBBP
- EP300
- MLL2
- KMT2D
- Mutations in CDKN2A alters cell cycle control and affects JAK–STAT signalling.
- Upregulation of key signalling pathways such as CD79B, MYD88, CARD11.
- Block to terminal differentiation such as BCL6 translocations and loss of PRDM1.
Associated Conditions
Gross Pathology
- For information on gross pathology findings of Follicular lymphoma, click here.
- For information on gross pathology findings of Mantle cell lymphoma, click here.
- For information on gross pathology findings of Hairy cell leukemia, click here.
- For information on gross pathology findings of Splenic marginal zone lymphoma, click here.
- For information on gross pathology findings of Mycosis fungoides, click here.
- For information on gross pathology findings of Peripheral T cell lymphoma, click here.
Microscopy Pathology
- For information on microscopic pathology findings of Follicular lymphoma, click here.
- For information on microscopic pathology findings of Mantle cell lymphoma, click here.
- For information on microscopic pathology findings of Hairy cell leukemia, click here.
- For information on microscopic pathology findings of Splenic marginal zone lymphoma, click here.
- For information on microscopic pathology findings of Mycosis fungoides, click here.
- For information on microscopic pathology findings of Peripheral T cell lymphoma, click here.
References
- ↑ 1.0 1.1 Morton LM, Zheng T, Holford TR, Holly EA, Chiu BC, Costantini AS; et al. (2005). "Alcohol consumption and risk of non-Hodgkin lymphoma: a pooled analysis". Lancet Oncol. 6 (7): 469–76. doi:10.1016/S1470-2045(05)70214-X. PMID 15992695.
- ↑ 2.0 2.1 Wang SS, Flowers CR, Kadin ME, Chang ET, Hughes AM, Ansell SM; et al. (2014). "Medical history, lifestyle, family history, and occupational risk factors for peripheral T-cell lymphomas: the InterLymph Non-Hodgkin Lymphoma Subtypes Project". J Natl Cancer Inst Monogr. 2014 (48): 66–75. doi:10.1093/jncimonographs/lgu012. PMC 4155466. PMID 25174027.
- ↑ Morton LM, Slager SL, Cerhan JR, Wang SS, Vajdic CM, Skibola CF; et al. (2014). "Etiologic heterogeneity among non-Hodgkin lymphoma subtypes: the InterLymph Non-Hodgkin Lymphoma Subtypes Project". J Natl Cancer Inst Monogr. 2014 (48): 130–44. doi:10.1093/jncimonographs/lgu013. PMC 4155467. PMID 25174034.
- ↑ Tamaru JI (2017). "2016 revision of the WHO classification of lymphoid neoplasms". Rinsho Ketsueki. 58 (10): 2188–2193. doi:10.11406/rinketsu.58.2188. PMID 28978864.
- ↑ 5.0 5.1 Swerdlow SH, Campo E, Pileri SA, Harris NL, Stein H, Siebert R; et al. (2016). "The 2016 revision of the World Health Organization classification of lymphoid neoplasms". Blood. 127 (20): 2375–90. doi:10.1182/blood-2016-01-643569. PMC 4874220. PMID 26980727.
- ↑ Matutes E (2018). "The 2017 WHO update on mature T- and natural killer (NK) cell neoplasms". Int J Lab Hematol. 40 Suppl 1: 97–103. doi:10.1111/ijlh.12817. PMID 29741263.
- ↑ Pasqualucci L, Trifonov V, Fabbri G, Ma J, Rossi D, Chiarenza A; et al. (2011). "Analysis of the coding genome of diffuse large B-cell lymphoma". Nat Genet. 43 (9): 830–7. doi:10.1038/ng.892. PMC 3297422. PMID 21804550.
- ↑ Lohr JG, Stojanov P, Lawrence MS, Auclair D, Chapuy B, Sougnez C; et al. (2012). "Discovery and prioritization of somatic mutations in diffuse large B-cell lymphoma (DLBCL) by whole-exome sequencing". Proc Natl Acad Sci U S A. 109 (10): 3879–84. doi:10.1073/pnas.1121343109. PMC 3309757. PMID 22343534.
- ↑ Green MR, Gentles AJ, Nair RV, Irish JM, Kihira S, Liu CL; et al. (2013). "Hierarchy in somatic mutations arising during genomic evolution and progression of follicular lymphoma". Blood. 121 (9): 1604–11. doi:10.1182/blood-2012-09-457283. PMC 3587323. PMID 23297126.