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

Cite this page: MALT lymphoma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/colontumorMALT.html. Accessed April 23rd, 2017.
Definition / General
  • Rare in colon
  • Usually adults
  • Often relapses but usually only in GI tract
Case Reports
Treatment
Gross Images

Images hosted on other servers:

flat elevated tumor with slight depression

Micro 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
Micro Images

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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