Evaluation of interphase fluorescence in situ hybridization for the t(14;18)(q32;q21) translocation in the diagnosis of XXXX on fine-needle aspirates: a comparison with flow cytometry immunophenotyping.

@entity1071 @entity588 @entity1075 @entity706 @entity1072 @entity2282 @entity1892 @entity1073 @entity12293
BACKGROUND: Diagnosing @entity1071 on fine-needle aspiration (FNA) can be challenging due to variable cellularity and lack of architecture. Ancillary studies often are required for diagnosis. @entity706 ( @entity706 ) is characterized by a monoclonal B-cell proliferation with coexpression of @entity1075 / @entity2282 and a t(14;18)(q32;q21) reciprocal translocation, resulting in the immunoglobulin heavy chain/ @entity588 fusion gene. These features also can be found, with much lower frequency, in diffuse large @entity1892 (DLBCL) of follicle center cell origin. The objective of the current study was to compare the accuracy in detecting @entity706 and DLBCL of follicle center cell origin by interphase fluorescence in situ hybridization (I-FISH) versus flow cytometry immunophenotyping (FCM) on FNAs. METHODS: Concurrent testing by FISH for t(14;18)(q32;q21) and FCM was performed on 84 FNAs, including 40 FLs and 44 non-FLs (de novo DLBCLs, @entity1073 , @entity1072 / @entity1072 [SLLs/CLLs], small @entity1892 , and @entity12293 ). The final diagnosis was rendered based on the combined information from cytomorphology, FCM, FISH, immunocytochemical staining for Ki-67, monoclonality for kappa and lambda light chains, and, if available, corresponding tissue biopsy, cytogenetic analysis, and polymerase chain reaction analysis. RESULTS: Among 40 FLs, FISH produced positive results for the t(14;18) translocation in 85.0%, negative results in 7.5%, and insufficient results in 7.5%; whereas, with FCM, 75% of cases exhibited a @entity1075 -positive ( @entity1075 +)/ @entity2282 + population (28 monoclonal, 2 nonclonal), 12.5% of cases exhibited a @entity1075 +/ @entity2282 -negative population (3 monoclonal, 2 nonclonal), and 12.5% of cases were insufficient. All of nonclonal results from FCM and all of the insufficient results from FCM analysis exhibited unequivocal t(14;18) translocation by FISH. In contrast, the three negative results and the three insufficient results from FISH were monoclonal and @entity1075 +/ @entity2282 + on FCM. The results from FISH and FCM were concordant in 75% cases. Of 44 non-FLs, FISH produced positive results for the t(14;18) translocation in 5 DLBCLs and 2 SLLs/CLLs. The latter showed single fusion signals just above the cutoff level. All cases in the non- @entity706 group that failed to show clonality or had insufficient results from FCM were DLBCLs. Among 17 DLBCLs, FISH detected a t(14;18) translocation in 29.4%, whereas FCM demonstrated a @entity1075 +/ @entity2282 + population in 23.5%. CONCLUSIONS: I-FISH for the t(14;18)(q32;q21) translocation provided high overall accuracy in detecting FLs on FNAs. This test can be used for diagnosing or monitoring @entity706 on FNAs when cellularity is limited or when FCM results are noncontributory. For detecting a follicle center cell origin in DLBCLs, I-FISH for the t(14;18) translocation appeared to be slightly more sensitive than FCM for the @entity1075 +/ @entity2282 + immunophenotype.
