MALT lymphoma

Colon tumor
Lymphoma and hematopoietic lesions
MALT lymphoma

Author: Charanjeet Singh, M.D. (see Authors page)

Revised: 3 January 2017, last major update February 2012

Copyright: (c) 2003-2017, PathologyOutlines.com, Inc.

PubMed Search: MALT [title] lymphoma colon

Table of Contents

Cite this page: MALT lymphoma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/colontumorMALT.html. Accessed July 14th, 2017.

Definition / general

Rare in colon
Usually adults
Often relapses but usually only in GI tract

Case reports

67 year old man with lymphomatoid polyposis (Am J Gastroenterol 1999;94:2540)
75 year old woman (World J Gastroenterol 2006;12:5573)

Treatment

Early tumors are focal and curable by surgery
Antibiotics may cause regression (J Gastroenterol 2005;40:843, Endoscopy 2002;34:343)

Gross images

Images hosted on other servers:

flat elevated tumor with slight depression

Microscopic (histologic) description

Small atypical lymphocytes with irregular nuclei, lymphoepithelial lesions
Reactive germinal centers and plasmacytic cells are common

Can be graded as:

Grade 0: Normal - plasma cells in lamina propria, no lymphoid follicles
Grade 1: Chronic active inflammation - lymphocyte clusters in lamina propria, no follicles and no lymphoepithelial lesions
Grade 2: Chronic active inflammation with florid lymphoid follicle formation - prominent follicles with surrounding mantle zone and plasma cells, no lymphoepithelial lesions
Grade 3: Suspicious lymphoid infiltrate in lamina propria, probably reactive - follicles surrounded by lymphocytes that infiltrate diffusely in lamina propria and / or epithelium
Grade 4: Suspicious lymphoid infiltrate in lamina propria, probably lymphoma - follicles surrounded by centrocyte-like, marginal zone cells that infiltrate diffusely in lamna propria and epithelium
Grade 5: Marginal zone (MALT) lymphoma - dense diffuse infiltrate of centrocyte-like, marginal zone cells in lamina propria with prominent lymphoepithelial lesions

Post therapy grading:

Complete histologic remission:
- Absent or scattered plasma cells and small lymphoid cells in the lamina propria
- No lymphoepithelial lesions
- Normal or empty lamina propria and / or fibrosis
Probable minimal residual disease:
- Aggregates of lymphoid cells or lymphoid nodules in the lamina propria and / or muscularis mucosa and / or submucosa
- No lymphoepithelial lesions
- Empty lamina propria and / or fibrosis
Responding residual disease:
- Dense, diffuse or nodular extending around glands in the lamina propria
- Lymphoepithelial lesions, may or may not be present
- Focal empty lamina propria and / or fibrosis
No response:
- Dense, diffuse or nodular lymphoid infiltrates
- Lymphoepithelial lesions, may or may not be present
- No changes in the stroma

Microscopic (histologic) images

Images hosted on other servers:

Figures A - D

Lymphocytes
immunohistochemically
showing diffusely positive
staining for L26

Lymphoma cells infiltrated into mucosal and submucosal layers

Molecular / cytogenetics description

Usually trisomy 3 or 18, less commonly t(1;14)(p22;q32, Gut 2006;55:1581 or t(11;18)(q21;q21) in 15% (Mod Pathol 2003;16:1232)
T(11;18) produces API2-MALT1 fusion gene; these tumors usually occur in males and are larger with more advanced stage
API2-MALT1 negative tumors usually occur in females