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Extranodal Marginal Zone Lymphoma of Mucosa-Associated Lymphoid Tissue (MALT lymphoma)
Definition / Description of Disease
Extranodal lymphoma composed of morphologically heterogeneous small B cells, including marginal zone (centrocyte-like) cells, monocytoid cells, small lymphocytes, and scattered immunoblasts and centroblast-like cells [1]. Plasmacytic differentiation present in some cases.
Infectious, chronic inflammatory, or autoimmune conditions are implicated in pathogenesis of MALT lymphoma.
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Site specific:
Stomach:
Can be asymptomatic or cause epigastric pain, anorexia, weight loss, anemia, early satiety, occasionally fever and night sweat
Associated with Helicobacter pylori infection (32% - >90%)[7][8][9]
> 75% of cases respond to H. pylori eradication with regression of lymphoma
H. pylori eradication therapy is 1st-line treatment; Chemotherapy ± radiation if DLBCL transformation or disseminated
Cases with t(11;18)(q21;q21) are resistant to H. pylori eradication therapy
5-year overall survival ~ 90%
Other organs: Mass and associated symptoms, higher chance of multiple site involvement and bone marrow involvement than gastric MALT lymphoma
Small bowel: Associated with Campylobacter jejuni infection in patients with α-heavy chain disease
Ocular adnexa: Associated with Chlamydia psittaci
Skin: Associated with Borrelia burgdorferi
Lung: Associated with Sjögren syndrome, cough and dyspnea (ref)
Salivary glands: Associated with Sjögren syndrome
Thyroid: Associated with Hashimoto thyroiditis
Most are low stage (stage I and II) at presentation, with up to 40% have disease with multiple sites involvement and up to 20% of patients have bone marrow involvement, and both are associated with non-gastric MALT lymphoma
Disseminated disease is usually refractory to chemotherapy
Recurrences may involve other extranodal sites
Serum paraprotein can be detected in one third of patients, particularly those with plasmacytic differentiation [10]. May be associated with Waldenström macroglobulinemia[11]
Sites of Involvement
Localized disease (most patients)
Stomach (35%, m/c)
Eyes and ocular adnexa (13%)
Lung (9%)
Skin (9%)
Salivary glands (8%)
Breasts (3%)
Thyroid (2%)
Bone marrow involvement in minority of patients (2-20%)
Multiple extranodal sites involvement
Higher in non-gastric MALT lymphoma cases
Generalized nodal involvement is rare (<10%)
Morphologic Features
Lymphoepithelial lesion
Specific but not sensitive, most prominent in thyroid and parotid glands
Can be present in some reactive conditions or in other lymphoma subtype
Infiltration and distortion of epithelial structures/glands (> 3 centrocyte-like cells causing epithelial damage)
Epithelial degeneration and glandular structure destruction
Diffuse or nodular pattern of growth
Expansion of marginal zone by cytologically heterogeneous cell population
Predominantly atypical centrocyte-like cells with small, cleaved, irregular nuclei with abundant cytoplasm
Monocytoid appearance with distinct rim of clear cytoplasm
Scattered large cells (centroblasts or immunoblasts) are present; up to 10% of all cells
Plasmacytic differentiation ± Dutcher bodies or Russell bodies (m/c in thyroid lymphoma)
Amyloid deposition
Transformation to diffuse large B-cell lymphoma
Large cells form sheets or large clusters of > 20 cells
May coexist with MALT lymphoma at initial presentation
Multifocal disease
~ 25% of patients have > 1 extranodal site of involvement
Immunophenotype
Finding
Marker
Positive (universal)
B cell associated markers (CD19, CD20, CD22, CD79a, PAX5)
CD21, CD23, CD35: Disrupted and expanded meshwork of follicular dendritic cells)
BCL2
CD11c
Miscellaneous
Keratin: can accentuate lymphoepithelial lesions
Congo red: can highlight amyloid deposition present in a subset of cases
Chromosomal Rearrangements (Gene Fusions)
Put your text here and fill in the table
Chromosomal Rearrangement
Genes in Fusion (5’ or 3’ Segments)
Pathogenic Derivative
Prevalence
Diagnostic Significance (Yes, No or Unknown)
Prognostic Significance (Yes, No or Unknown)
Therapeutic Significance (Yes, No or Unknown)
Notes
EXAMPLE t(9;22)(q34;q11.2)
EXAMPLE 3'ABL1 / 5'BCR
EXAMPLE der(22)
EXAMPLE 20% (COSMIC)
EXAMPLE 30% (add reference)
Yes
No
Yes
EXAMPLE
The t(9;22) is diagnostic of CML in the appropriate morphology and clinical context (add reference). This fusion is responsive to targeted therapy such as Imatinib (Gleevec) (add reference).
Put your text here and fill in the table (Instructions: Includes aberrations not involving gene fusions. Can include references in the table. Can refer to CGC workgroup tables as linked on the homepage if applicable.)
Chr #
Gain / Loss / Amp / LOH
Minimal Region Genomic Coordinates [Genome Build]
Minimal Region Cytoband
Diagnostic Significance (Yes, No or Unknown)
Prognostic Significance (Yes, No or Unknown)
Therapeutic Significance (Yes, No or Unknown)
Notes
EXAMPLE
7
EXAMPLE Loss
EXAMPLE
chr7:1- 159,335,973 [hg38]
EXAMPLE
chr7
Yes
Yes
No
EXAMPLE
Presence of monosomy 7 (or 7q deletion) is sufficient for a diagnosis of AML with MDS-related changes when there is ≥20% blasts and no prior therapy (add reference). Monosomy 7/7q deletion is associated with a poor prognosis in AML (add reference).
EXAMPLE
8
EXAMPLE Gain
EXAMPLE
chr8:1-145,138,636 [hg38]
EXAMPLE
chr8
No
No
No
EXAMPLE
Common recurrent secondary finding for t(8;21) (add reference).
editv4:Individual Region Genomic Gain / Loss / LOH
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Put your text here (EXAMPLE PATTERNS: hyperdiploid; gain of odd number chromosomes including typically chromosome 1, 3, 5, 7, 11, and 17; co-deletion of 1p and 19q; complex karyotypes without characteristic genetic findings; chromothripsis)
Chromosomal Pattern
Diagnostic Significance (Yes, No or Unknown)
Prognostic Significance (Yes, No or Unknown)
Therapeutic Significance (Yes, No or Unknown)
Notes
EXAMPLE
Co-deletion of 1p and 18q
Yes
No
No
EXAMPLE:
See chromosomal rearrangements table as this pattern is due to an unbalanced derivative translocation associated with oligodendroglioma (add reference).
Gene Mutations (SNV / INDEL)
Put your text here and fill in the table (Instructions: This table is not meant to be an exhaustive list; please include only genes/alterations that are recurrent and common as well either disease defining and/or clinically significant. Can include references in the table. For clinical significance, denote associations with FDA-approved therapy (not an extensive list of applicable drugs) and NCCN or other national guidelines if applicable; Can also refer to CGC workgroup tables as linked on the homepage if applicable as well as any high impact papers or reviews of gene mutations in this entity.)
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MALT lymphoma presents somatically mutated immunoglobulin heavy chain variable region (IGHV) genes in nearly all cases. Site specific.[18]
IGHVH1-69 in salivary gland lymphomas
IGHVH3-30 or IGHVH3-23 in gastric MALT lymphomas responsive to H pylori eradication and without the t(11;18) translocation
IGHVH4-34 in orbital adnexal lymphomas
IGHV3 and IGHV4 families in pulmonary lymphomas
IGHVH1-69 or IGHVH4-59 in cutaneous lymphomas
Gene; Genetic Alteration
Presumed Mechanism
(Tumor Suppressor Gene [TSG] / Oncogene / Other)
Prevalence
Notes
TNFAIP3
NF-κB negative regulator
29%
Mutations includes deletions, SNVs, and promoter methylation, can be present in cases lacking specific translocations listed above. Mutations can be also found in many types of NHL.
↑Swerdlow, SH. et al., (2017) WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues. International Agency for Research on Cancer (p 159-262).
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*Citation of this Page: “Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue”. Compendium of Cancer Genome Aberrations (CCGA), Cancer Genomics Consortium (CGC), updated 09/3/2024, https://ccga.io/index.php/HAEM5:Extranodal_marginal_zone_lymphoma_of_mucosa-associated_lymphoid_tissue.