title: Immunophenotypic features and t(14;18) (q32;q21) translocation of Chinese follicular lymphomas helps to distinguish subgroups.
abstract: BACKGROUND
  The revised 2008 World Health Organization classification maintains a histological grading system (grades 1-3) for follicular lymphoma (FL). The value of grading FL has been debated. This study will yield deeper insights into the morphologic, immunophenotypic characterization and t(14;18) translocation in FL and explore their significance of diagnosis of Chinese FL subgroups.
  
  
  METHODS
  We retrospectively reviewed the FL diagnoses according to the 2008 WHO classification in all diagnostic specimens from a multicentric cohort of 122 Chinese patients. Upon review, 115 cases proved to be truly FL. CD10, BCL6, MUM1, BCL2 and t(14;18) (q32;q21) translocation were detected by Envision immunostaining technique and fluorescence in situ hybridization.
  
  
  RESULTS
  FL1 has larger proportion of follicular pattern (93.0%) than that of FL2 (73.7%, P = 0.036), FL3B (63.6%, P = 0.003) and FL3A (77.4%, P = 0.053), although the last P value was more than 0.05 (Pearson's chi-squared test). Areas of DLBCL were present in 25.8% (8/31) of FL3A and more frequent in FL3B (59.1%, 13/22; P = 0.015). The positivity of CD10 and BCL2 in FL1-2 were significantly higher than those in FL3 (P < 0.001, P = 0.043, respectively). The positivity of MUM1 in FL1-2 was significantly lower than that in FL3 (10.2% vs. 51.0%; P < 0.001). Furthermore the positivity of MUM1 in FL3A was significantly lower than that in FL3B (37.9% vs. 68.2%; P = 0.032). The positivity of t(14;18) was higher in FL1-2 than in FL3 (73.5% vs. 35.6%, P < 0.001), and was higher in FL3A than in FL3B (51.9% vs. 11.1%, P = 0.005). t(14;18) was significantly correlated with CD10+ (R = 0.453, P < 0.001) and MUM1+ (R = -0.482, P < 0.001).
  
  
  CONCLUSIONS
  FL1 and FL2 were immunophenotypically and genomically similar, while FL3A and FL3B were partly immunophenotypically similar but morphologically, genomically distinct. FL3A was genomically closer to FL1-2, whereas FL3A was genomically closer DLBCL. Thus we hypothesize that FL may in fact be a heterogeneous indolent lymphoma encompassing entities with distinct molecular pathogenesis and genetic characteristics. Immunohistochemical and genetic characterization helps to distinguish subgroups of FLs.
  The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1334018129864616.
authors.affiliation: Department of Pathology, Guangdong General Hospital, Guangdong Academy of Medical Science, Guangzhou 510080, China. yanh_liu@163.com.
authors.forename: Fen
authors.initials: F
authors.lastname: Zhang
authors.forename: Li-Xu
authors.initials: LX
authors.lastname: Yan
authors.forename: Su-Xia
authors.initials: SX
authors.lastname: Lin
authors.forename: Zi-Yin
authors.initials: ZY
authors.lastname: Ye
authors.forename: Heng-Guo
authors.initials: HG
authors.lastname: Zhuang
authors.forename: Jing-Ping
authors.initials: JP
authors.lastname: Yun
authors.forename: Han-Liang
authors.initials: HL
authors.lastname: Lin
authors.forename: Dong-Lan
authors.initials: DL
authors.lastname: Luo
authors.forename: Fang-Ping
authors.initials: FP
authors.lastname: Xu
authors.forename: Xin-Lan
authors.initials: XL
authors.lastname: Luo
authors.forename: Jie
authors.initials: J
authors.lastname: Cheng
authors.forename: Ke-Ping
authors.initials: KP
authors.lastname: Zhang
authors.forename: Yan-Hui
authors.initials: YH
authors.lastname: Liu
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000032:analysis* / Q000235:genetics*; D002681:China; D002883:Chromosomes, Human, Pair 14; D002887:Chromosomes, Human, Pair 18; D003937:Diagnosis, Differential; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D007150:Immunohistochemistry; D016130:Immunophenotyping / Q000379:methods; D017404:In Situ Hybridization, Fluorescence; D008224:Lymphoma, Follicular / Q000737:chemistry* / Q000145:classification / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D010641:Phenotype; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D014178:Translocation, Genetic; D055815:Young Adult
chemical_list: D014408:Biomarkers, Tumor
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