title: Early lymph node involvement by mantle cell lymphoma limited to the germinal center: report of a case with a novel "follicular in situ" growth pattern.
abstract: Recently, several reports have described cases of "in situ" mantle cell lymphoma (MCL) in which scattered cyclin D1+ cells were present within the mantle zones of reactive-appearing lymphoid follicles. In this report, we describe an unusual histologic pattern of in situ MCL that was identified in a staging lymph node for colonic adenocarcinoma resected 4 years before a diagnosis of symptomatic MCL. Retrospective immunohistochemical studies showed scattered cyclin D1-expressing cells within otherwise reactive germinal centers but not in the surrounding mantle zones. The presence of early MCL cells limited to reactive germinal centers represents a novel "follicular in situ" growth pattern for MCL, which overlaps morphologically with reactive follicular hyperplasia and follicular lymphoma and which could have implications for MCL pathogenesis.
authors.affiliation: Dept of Laboratory Medicine, University of Washington, Seattle, WA 98109, USA.
authors.forename: Kerstin L
authors.initials: KL
authors.lastname: Edlefsen
authors.forename: Harvey A
authors.initials: HA
authors.lastname: Greisman
authors.forename: Hye Son
authors.initials: HS
authors.lastname: Yi
authors.forename: Kristin M
authors.initials: KM
authors.lastname: Mantei
authors.forename: Jonathan R
authors.initials: JR
authors.lastname: Fromm
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology; D000368:Aged; D003110:Colonic Neoplasms / Q000473:pathology; D003951:Diagnostic Errors; D015326:Gene Rearrangement, B-Lymphocyte, Heavy Chain; D018858:Germinal Center / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry; D008198:Lymph Nodes / Q000378:metabolism / Q000473:pathology*; D008224:Lymphoma, Follicular / Q000473:pathology*; D020522:Lymphoma, Mantle-Cell / Q000378:metabolism / Q000473:pathology*; D008297:Male; D009378:Neoplasms, Multiple Primary / Q000473:pathology; D016133:Polymerase Chain Reaction