3. Mucosa-associated lymphoid tissue (MALT)
is scattered along mucosal linings in the
human body and constitutes the most
extensive component of human lymphoid
tissue. These surfaces protect the body from
an enormous quantity and variety of
antigens. The tonsils, the Peyer patches
within the small intestine, and
the vermiform appendix are examples of
MALT.
4. MALT is understood to include
1. gut-associated lymphoid tissue (GALT)
2. bronchial/tracheal-associated
lymphoid tissue (BALT)
3. nose-associated lymphoid tissue (NALT)
4. vulvovaginal-associated lymphoid
tissue (VALT)
Additional MALT exists within the
accessory organs of the digestive tract,
predominantly the parotid gland.
5. The most prominent
concentration of native mucosa
associated lymphoid tissue(MALT)
is seen in the terminal ileum in
the form of Peyer’s patches, and
for this reason the term
Lymphoma of MALT applied to this
group of lymphoma.
7. GI LYMPHOID TISSUE
Four lymphoid compartments :
Organized mucosal lymphoid tissue - Peyer’s
patches in the terminal ileum
The lamina propria
Intraepithelial lymphocytes
Mesenteric lymph nodes
8. PEYER'S PATCH
Unencapsulated
organized lymphoid
nodules in small
intestine, the appendix
and colorectum
Architecture similar to
Lymph node
Mantle zone - IgM+,
IgD+
Marginal zone - IgM+,
IgD-
9. Peyer patches are unencapsulated aggregates of lymphoid
cells that bear certain resemblance to lymph node.
It consist of B and T cell areas and associated accessory
cells.
The B cell area is composed of a germinal centre
surrounded by a mantle zone of small B lymphocytes,
which is broadest at the mucosal aspect of the follicle.
Surrounding the mantle zone is a broad marginal zone in
which most of the cells are intermediate sized B
lymphocytes with moderately abundant, pale staining
cytoplasm and nuclei with a slightly irregular outline
leading to a resemblance to centrocytes.
10. The marginal zone extends towards the mucosal surface
and some marginal zone B cells enter the overlying
dome shaped epithelium, where they form the
lymphoepithelium, which is a defining feature of MALT.
The epithelium in this area contains a population of
specially adapted cells, M cells, which facilitate the
transport of large molecules across the epithelial barrier.
The area around follicle contains T-cells, plasma cells
and accessory cells.
12. Dome epithelium showing intraepithelial B
lymphocytes constituting the lymphoepithelium
that defines mucosa associated lymphoid tissue
Intraepithelial B
lymphocyte
13. IEL(intra epithelial
lymphocytes)
Phenotypically heterogeneous
population
MC- CD3+, CD4-, CD8+, CD5-,
CD103+ cytotoxic T- cells that use αβ
T-cell receptor (TCR)
CD4-, CD8-, and uses γδTCR.
CD56-positive IELs, virtually
undetectable in normal mucosa
Mesentric Lymphnode
Inactive B-cell follicles
Prominent marginal zone
Prominent dilated sinuses often
containing transformed B-blasts.
Poorly developed paracortex
Lamina propria
Plasma cells, macrophages, and to
a lesser extent, B and T cells
Predominantly secrete IgA
CD4/CD8 ratio 4:1
Express CD 103
15. MALT Lymphoma is listed in the WHO classification
under the designation of extranodal marginal zone
lypmphoma of mucosa associated lymphoid
tissue(MALT).
It is defined as lymphoma that recapitulates the
histology of MALT(Peyer Patch), the normal cell
counterpart is marginal zone B cell.
It typically arise in areas devoid of constitutive
organised lymphoid tissue.
It consist of morphologically heterogenous small B cells
including the marginal zone (centrocytes) cells, cells
resembling monocytoid cells, small lymphocytes, and
scattered immunoblast and centroblast like cells.
19. Extranodal marginal zone lymphoma of MALT
lymphoma is the 4th commonest B cell non-
Hodgkin’s lymphoma(NHL) worldwide.
Accounting for about 9% of all B cell lymphoma
Most commonly encountered in GI tract with
stomach the most frequently involved.
Most cases are middle aged and elderly, usually
over 50 years.
Slight female preponderance.
Higher incidence in Europe that have higher
rates of infection with H. Pylori.
21. Rarely arise from the native lymphoma
Ususally arise from MALT that is acquired as a
result of chronic inflammatory disorder at sites
normally devoid of MALT, including the stomach.
Most commonly as result of infection with
Helicobacter Pylori, which precedes the
development of most cases of gastric MALT
lymphoma.
Also can be seen with infection by Helicobacter
heilmannii and in patients with Sjogren’s
syndrome.
23. Infection with H. Pylori results in
Active chronic inflammation with B cell follicles and formation of
lymphoepithelium by B-cell infiltration of glands immediately
adjacent to the follicles but the specialised M cells are not seen.
Between the follicles, the gastric mucosal lamina propria is infiltrated
by T lymphocytes, plasma cells, macrophages, and occasional
collections of neutrophils.
Immunohistochemically, the B cell follicles shows IgM and IgD positive
mantle zone cells while lymphoma cells are IgM+ and IgD-
24. Gastric biopsy showing Helicobacter
pylori associated chronic gastritis
resulting in
acquisition of mucosa-associated
lymphoid tissue by gastric antral mucosa
Normal gastric antral mucosa.
There is no organized lymphoid
tissue
27. ENDOSCOPY
It may form a single
dominant mass with
erythema, thickened
folds and erosions
Polyps may be seen
Occasionally a more
solid lesion with or
without ulceration is
seen
29. Early stage
Closely resembles the normal MALT.
Expansion of the marginal zone around reactive follicles, that
may have intact mantles.
Cells in the marginal zone are composed of, centrocyte
type cells - closely resemble small lymphocytes with
abundant pale cytoplasm and well-defined cell
borders, cells resembling monocytoid cells, small
lymphocytes, and scattered immunoblast and centroblast like
cell.
Dutcher bodies may be seen.
Variable plasma cell infiltrate in one-third of MALT
lymphomas
31. Histological features of gastric MALT lymphoma(A)
Lymphomatous infiltrate forming lymphoepithelial lesions
(B–D) cytology of neoplastic marginal zone cells (E) plasma
cell differentiation
32. Followed by
Infiltration of neoplastic cells into the gland/crypt
epithelium with destruction of architecture resulting
in lymphoepithelial lesions.
In the earliest stages these can be recognised by
clusters of 3 or more cytologically atypical neoplastic
cells in the epithelium.
With the disease progression the intact lymphoid
follicle are overrun by lymphoma cells and there
presence can only be demonstrated by
immunostatining with follicular dendritic cells(FDC).
33. Lymphoepithelial lesions in a case of gastric
mucosa-associated lymphoid tissue
lymphoma distorting glands and associated
with eosinophilic change of gastric
epithelium.
Gastric mucosa-associated
lymphoid tissue lymphoma
showing a
characteristic lymphoepithelial
lesion
35. Pan B cell markers such as CD19, CD20, CD22,
CD79a, and PAX5 are positive.
Aberrant expression of CD 43 in about 50% of cases.
Surface Ig- IgM or IgA, and rarely IgG.
Negative for CD5, CD23, cyclinD1, CD10 and bcl-6
Staining for FDC- antibodies to CD21 and/or CD23
Staining for cytokeratin-highlight the
lymphoepithelial lesions
Antibodies to bcl-6 and CD10-residual germinal
centres.
Light chain restriction(kappa more than lambda)
37. t(11;18)(q21;q21)- API2-MALT1- present in about 25%.
This creates a novel functioning fusion product by
translocating the terminus region of apoptosis inhibitor 1
(API1) gene to the carboxy terminus of MALT1.—this activate
the NF-kB pathways.
t(1;14)(p22;q32) -BCL10-IGH-
present in about 5% of gastric MALT lymphomas,
translocation of the BCL-10 gene into to come under influence
of immunoglobulin heavy chain(IGH) gene
trisomies 3, 12, and 18
39. Subtype of MALT lymphoma
Frequently encountered in the Middle East,
Mediterranean countries and Cape region of South
Africa and in some parts of Indian sub-continent.
at any age but mainly in young adults (range, 10-35
years; mean, 25-30 years)
Associated with infection with campylobacter jejuni
Type of MALT lymphoma is associated with synthesis of
abnormal IgA chain
May transform into large cell lymphoma
40.
41. HISTOPATHOLOGY
Stage A
Lymphoplasmacytic infiltrate is confined to the mucosa and mesenteric
lymph nodes
No cytological atypia
Endoscopic examination appears normal- responsive to antibiotic therapy
Stage B
Nodular mucosal infiltrates develop and there is extension below the
muscularis mucosae
Minimal degree of cytological atypia
Occasional immunoblast like cells
Endoscopically as thickening of mucosal folds
42. Stage C
Presence of large masses and
transformation to frank large
cell lymphoma.
Numerous centroblasts and
immunoblasts are present.
Plasmacytic differentiation is
still evident
Marked cytological atypia
including Reed-Sternberg-like
cells.
Mitotic activity is increased
43. Imunophenotypically similar to classic
MALT lymphoma.
Plasma cells show synthesis of IgA (usually
IgA1) and light chain production is absent.
Serum and duodenal juice shows raised
levels of IgA.
45. Features differentiating lymphoma are:
Expansion of the marginal zone with extension of small
B cells away from the immediate confines of the follicle,
extending into the mucosa around epithelial structures
Presence of moderate cytological atypia, Dutcher
bodies, and formation of genuine lymphoepithelial
lesions
Special techniques
CD43+
Molecular studies
BIOMED-2 primer/protocol
Optimised protocol/heteroduplex analysis
REACTIVE LYMPHOID INFILTRATES
46. OTHER B-CELL LYMPHOMAS
Follicular lymphoma: Presence of a significant
extrafollicular component
CD10+, bcl-6+, aberrant expression of bcl-2 protein
Mantle cell lymphoma : CD5+, cyclinD1 staining
CLL/SLL: CD5+/CD23+
Burkitt lymphoma: CD19,CD20,CD22,surface IgM
positive; 60-80% of cases CD10 positive
Diffuse B-cell lymphoma: CD10+ or CD10−, bcl6+,
47. WHO Committee for the classification of Tumours of the
Digestive System states that:
“For the distinction between reactive and
neoplastic infiltrates, histologic evaluation
remains the gold standard but the accessory
studies may be helpful”
Wotherspoon et al. devised a useful grading
system by which to indicate the degree of
certainty of diagnosis.
50. All the patients with GI lymphoma should have an
endoscopy
Standard staging workup and multiple deep gastric
biopsies must be taken and processed for lymphoma
and stain for H. Pylori.
51. Approximately 70% of gastric MALT lymphomas respond
to Hp eradication therapy alone with enduring
remission.
Determination of Hp status:
Histological evaluation
culture
Stool polymerase chain reaction based studies
Serological based studies- most accurate as
circulating antibodies may be present up to 2 years
following eradication.
52. Prediction of cases that will respond to Hp eradication
alone is important to the management of these patient.
No clinical, pathological or molecular feature will absolutely
predict those cases
Time to response is also variable- some showing response at
the time of first endoscopy done to assess Hp status while
others regress after months to years.
Success of Hp eradication should be confirmed by the
current clinical guidelines.
This include a urea breath test as the most accurate
determinant of presence of small residual colonies.
53. Antibiotic resistant cases should raise the
suspicion of presence of t(11;18) (q21;q21)
Diagnosis is done by
Interphase fluorescence in situ hybridisation
with MALT1 dual-color break-apart
API2-MALT1 dual color fusion probes
Reverse transcription polymerase chain
reaction (RTPCR) of the API2-MALT1 fusion
transcript
54. Persistent MALT lymphoma cases- more
conventional anti-lymphoma therapeutic
approaches are indicated.
Surgery is no longer indicated- due to
presence of microlymphoma foci.
Radiotherapy
Standard chemotherapy with or without
immunotherapy- chlorambucil or
cyclophosphamide or thalidomide.
56. The GELA group(Group d’Etude des
Lymphomes de l’Adulte) has developed a
scheme for assessment of post eradication
biopsies.
The scoring system assess the lymphoid
infiltrate in the mucosa, the degree of
regression associated fibrosis and the
presence of lymphoepithelial lesions and
divides the finding into four groups.
57. GELA category Morphological features Recommendation
CR-complete histological
response
Empty appearance of LP with
fibrosis,few glands,small
lymphocytes and plasma
cells; no LELs
No need of additional
therapy
pMRD-probable Minimal
Residual Disease
Base of lamina propria
and/or submucosa with
small lymphoid nodules and
fibrosis;no LELs
No need of additional
therapy
rRD-responding residual
diseas
Presence of lymphomatous
infiltrate in a diffuse or
nodular pattern, some
degree of stromal changes;
focal or no LELs
Evaluation of clinincal
progression should
delineate additional
therapy
NC-no change Dense lymphomatous
infiltrate similar to diagnostic
biopsy;LEL present
Oncological treatment
should be proposed if
infiltrate persists over
sequential
examinations
LP-lamina propria; LEL-lymphoepithelial lesion
59. Sequential follow up biopsies are indicated in all cases of
gastric MALT lymphoma.
In cases of relapse-repeat eradication therapy has been
proven effective.
There is risk of development of gastric adenocarcinomas
in these patients—can be detected by repeat biopsies.
For extra gastic MALT Lymphoma, antibiotic based
therapy may be effective in some cases but
chemotherapeutic strategies are generally involved.