Morphologic and Phenotypic Analysis of Cytogenetic Subsets of Follicular Lymphoma
Paul R Hosking, Daniela Hoehn, Vundavalli M Murty, Alobeid Bachir, Govind Bhagat. Columbia University Medical Center, New York, NY
Background: Follicular lymphoma (FL) is characterized by t(14;18) leading to BCL2 rearrangement (BCL2r+) in the majority of cases. Translocations involving chromosome 3q27 harboring BCL6 rearrangements (BCL6r+) have been described and multiple groups explored relations between these rearrangements and clinical parameters such as evolution and survival. Conflicting data exist regarding the impact of these genetic aberrations on morphologic and phenotypic characteristics of FL. In this study we assess associations between these rearrangements and immunoarchitectural patterns.
Design: We searched our cytogenetic database from 1997 to 2010 to identify 4 different cytogenetic subsets of FL: BCL2r+/BCL6r-; BCL2r+/BCL6r+; BCL2r-/BCL6r+; BCL2r-/BCL6r-. Cases were graded, morphologic features were assessed and immunohistochemical (IHC) expression profiles of CD10, bcl2, bcl6, MUM-1 and Ki67 were recorded. IHC analysis was scored semi quantitatively in a 4 tiered manner. Statistical analysis was performed using t-test and Mann-Whitney U test.
Results: Of 78 FL identified, 41 (52%) demonstrated BCL2r+/BCL6r-, 10 (13%) BCL2r+/BCL6r+, 9 (12%) BCL2r-/BCL6r+, and 18 (23%) BCL2r-/BCL6r-. BCL2r-/BCL6r+ cases displayed greater degrees of follicular fusion and higher grade (p=0.0652, p=0.020). They expressed increased Ki67 and decreased CD10 (p=0.0075, p<0.001). BCL2r+/BCL6r-, BCL2r+/BCL6r+ and BCL2r-/BCL6r- FL subsets did not show statistically significant differences in cyto-architectural features, the latter showed decreased bcl2 expression. Differences in MUM-1 and bcl6 expression were insignificant across all subsets. Increased age was associated with BCL2r+/BCL6r+ cases, however, no differences were seen in any other clinical parameters evaluated.
Conclusions: Our findings suggest that distinct morphologic and immunophenotypic features in FL are associated with BCL6 rearrangements but not with other types of cytogenetic aberrations. We did not discern any adverse clinical features associated with different cytogenetic subsets of FL evaluated. Biological implications of these findings need to be further elucidated.
Tuesday, March 5, 2013 1:00 PM
Poster Session IV # 254, Tuesday Afternoon