title: Multiple polypoid lesions of primary mucosa-associated lymphoid-tissue lymphoma of colon.
abstract: OBJECTIVE
  This study was focused on unusual cases of mucosa-associated lymphoid tissue (MALT) lymphoma presenting with multiple polypoid lesions of the colon and rectum with a special reference to the differential diagnosis of mantle cell lymphoma.
  
  
  RESULTS
  The lesions of these five cases grossly showed a segmental distribution of nodular protrusions in three patients and of innumerable small polyps in two. These patterns of involvement simulated those of multiple lymphomatous polyposis, known as the gastrointestinal presentation of mantle cell lymphoma (MCL), and caused a differential diagnostic problem between MALT lymphoma and MCL, which have different prognostic and therapeutic implications. Their histological features are almost indistinguishable from each other, especially in the small biopsy specimens via endoscope. The most important procedure for their differentiation is cyclin D1 immunohistochemistry and its negative reaction provides strong indication of MALT lymphoma. Of interest, one case showed a rare karyotypic abnormality of t(11;18)(q21;q21), which has been reported specifically in MALT lymphoma.
  
  
  CONCLUSIONS
  This study has indicated that the multiple polypoid lesions of the colon occur not only in MCL, but also in MALT lymphoma, making differential diagnosis between the two entities necessary, and cyclin D1 immunohistochemistry is indispensable for distinguishing between them.
authors.affiliation: Department of Pathology and Clinical Laboratories, Aichi Cancer Center Hospital, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Yatabe
authors.forename: S
authors.initials: S
authors.lastname: Nakamura
authors.forename: T
authors.initials: T
authors.lastname: Nakamura
authors.forename: M
authors.initials: M
authors.lastname: Seto
authors.forename: M
authors.initials: M
authors.lastname: Ogura
authors.forename: M
authors.initials: M
authors.lastname: Kimura
authors.forename: H
authors.initials: H
authors.lastname: Kuhara
authors.forename: T
authors.initials: T
authors.lastname: Kobayashi
authors.forename: M
authors.initials: M
authors.lastname: Taniwaki
authors.forename: Y
authors.initials: Y
authors.lastname: Morishima
authors.forename: T
authors.initials: T
authors.lastname: Koshikawa
authors.forename: T
authors.initials: T
authors.lastname: Suchi
mesh_terms: D000328:Adult; D000368:Aged; D003111:Colonic Polyps / Q000235:genetics / Q000276:immunology / Q000473:pathology*; D015179:Colorectal Neoplasms / Q000235:genetics / Q000276:immunology / Q000473:pathology*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D018442:Lymphoma, B-Cell, Marginal Zone / Q000235:genetics / Q000276:immunology / Q000473:pathology*; D008228:Lymphoma, Non-Hodgkin / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009378:Neoplasms, Multiple Primary / Q000235:genetics / Q000276:immunology / Q000473:pathology