Extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma)


An extra-nodal lymphoma of small B lymphoid cells including marginal zone (centrocyte-like) cells, monocytoid-like cells, small lymphocytes and scattered immunoblast and centrocyte-like cells. Some cases show plasma-cell differentiation. The infiltrate is seen in the marginal zone of B-cell follicles and in the interfollicular areas. There is infiltration of epithelia to form lymphoepithelial lesions.



7-8% of all B-cell lymphomas and 50% of gastric lymphomas.


The development of MALT lymphoma is commonly preceded by a history of chronic inflammation / autoimmune disease:

Anatomic sites

10% of cases have multiple extranodal sites at presentation. Bone marrow involvement is seen in 20% of patients and is more common with ocular and pulmonary disease, less common with GI disease.

Clinical features

Apart from IPSID, a monoclonal gammopathy is rare.


The neoplastic cells are first found in a marginal zone distribution, external to an intact mantle zone. Eventually there is interfollicular expansion and the follicles are overrun. The neoplastic cells have small to medium sized slightly irregular nuclei and relatively abundant cytoplasm, resembling centrocytes. With a larger amount of cytoplasm, they resemble monocytes and discrete aggregates of monocytoid cells are seen in a perisinusoidal distribution. Plasma cell differentiation occurs in one third of gastric cases and is usual in thyroid MALT lymphoma and IPSID. There are limited numbers of large blastic cells.

Lymphoepithelial lesions are characteristic. Colonisation of non-neoplastic follicles may give a resemblance to follicular lymphoma. Nodal involvement in gastric MALT lymphoma shows various patterns .








less often positive



less often positive


light chains

positive except in IPSID



may be aberrant nuclear positivity; 28/533









variably negative or weakly positive







a marginal zone cell-associated antigen






a marginal zone cell-associated antigen







CD21 and CD35 are likely to demonstrated the meshwork of expanded colonised follicles.


t(11;18)(q21;q21), t(1;14)(p22;q32) and t(14;18)(q32;q21) all seem to activate the NFkB pathway.

Differential diagnosis



features in lamina propria



scattered plasma cells but no lymphoid follicles


chronic active gastritis

small clusters of lymphocytes but no lymphoid follicles and no lymphoepithelial lesions


chronic active gastritis with florid lymphoid follicle formation

lymphoid follicles with surrounding mantle zone and plasma cells but no lymphoepithelial lesions


suspicious lymphoid infiltrate, probably reactive

lymphoid follicles surrounded by small lymphocytes that diffusely infiltrate the lamina propria and occasionally the epithelium


suspicious lymphoid infiltrate, probably lymphoma

lymphoid follicles surrounded by marginal zone cells that diffusely infiltrate the lamina propria and into the epithelium in small groups



MALT lymphoma

a dense infiltrate of marginal zone cells with prominent lymphoepithelial lesions


The course is usually indolent with slow dissemination to other extranodal sites. Transformation to Diffuse Large B-Cell Lymphoma may occur.


World Health Organization Classification of Tumours, Tumours of the haematopoietic and lymphoid tissues, IARC Press 2001.

1 SB Cogliatti et al. Significantly different bcl-2 expression profiles in gastric and non-gastric primary extranodal high-grade B-cell lymphomas. J Pathol 2000;192:470-478.

2 Wotherspoon AC, Doglioni C, Diss TC, et al. Regression of primary low-grade B-cell gastric lymphoma of mucosa-associated lymphoid tissue type after eradication of Helicobacter pylori. Lancet 1993; 342:575-7

3 Liu, H., H. Ye, et al. (2001). "T(11;18)(q21;q21) is associated with advanced mucosa-associated lymphoid tissue lymphoma that expresses nuclear BCL10." Blood 98(4): 1182-7, first published in abstract, Liu T et al. t(11;18)(q21;q21) is associated with more advanced MALT lymphoma that expresses nuclear bcl-10. J Pathol 2001:193(suppl):2A. FULL TEXT

4 Nishimura, M., Miyajima, S., Okada, N. Salivary gland MALT lymphoma associated with Helicobacter pylori infection in a patient with Sjogren's Syndrome. J Dermatol 2000;27:450-2.

5 Liu, H., Ruskon-Fourmestraux, A., Lavergne-Slove, A. et al. Resistance of t(11;18) positive gastric mucosa-associated lymphoid tissue lymphoma to Helicobacter pylori eradication therapy. Lancet 2001;357:39-40.

6 Ko, Y.H., Han, J.J., Noh, J.H. and Ree, H.J. Lymph nodes in gastric B-cell lymphoma: pattern of involvement and early histological changes. Histopathology 2002;40:497-504.

7 Li, C., H. Inagaki, et al. (2003). "Primary cutaneous marginal zone B-cell lymphoma: a molecular and clinicopathologic study of 24 asian cases." Am J Surg Pathol 27(8): 1061-9.

8 Okabe, M., H. Inagaki, et al. (2003). "API2-MALT1 fusion defines a distinctive clinicopathologic subtype in pulmonary extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue." Am J Pathol 162(4): 1113-22.

9 Inagaki, H., J. K. Chan, et al. (2002). "Primary thymic extranodal marginal-zone B-cell lymphoma of mucosa-associated lymphoid tissue type exhibits distinctive clinicopathological and molecular features." Am J Pathol 160(4): 1435-43.

10 Streubel, B., A. Lamprecht, et al. (2003). "T(14;18)(q32;q21) involving IGH and MALT1 is a frequent chromosomal aberration in MALT lymphoma." Blood 101(6): 2335-9.

11 Lecuit M, Abachin E, Martn A, et al. Immunoproliferative small intestinal disease associated with Campylobacter jejuni. N Engl J Med 2004; 350:239-48.

12 Parsonnet J,Isaacson PG Bacterial infection and MALT lymphoma. N Engl J Med 2004; 350:213-5

13 Ferreri AJ, Guidoboni M, Ponzoni M, et al. Evidence for an association between Chlamydia psittaci and ocular adnexal lymphomas. J Natl Cancer Inst 2004; 96:586-94

14 Joao C, Farinha P, da Silva MG, et al. Cytogenetic abnormalities in MALT lymphomas and their precursor lesions from different organs. A fluorescence in situ hybridization (FISH) study. Histopathology 2007; 50:217-24

This page last revised 29.1.2007.

©SMUHT/PW Bishop