Colon tumor - MALT lymphoma of colon

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Colon tumor

Lymphoma and hematopoietic lesions

MALT lymphoma of colon

Reviewers: Charanjeet Singh, M.D. (see Reviewers page)
Revised: 25 February 2012, last major update February 2012
Copyright: (c) 2003-2012, PathologyOutlines.com, Inc.

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

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

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

Micro description
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● 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 lympho-epithelial 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

Micro images
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Figures A-D

Figures 2, 4, 5

Molecular description
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● 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

End of Colon tumor > Lymphoma and hematopoietic lesions > MALT lymphoma of colon

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