[1604] GCB vs. ACB Protein Signature in Mantle Cell Lymphoma (MCL). MUM1 Expression Correlate with Proliferation Index (Ki-67) without Impact on Survival

Rabeya Zarrin, Lesley Street, Farid Kosari, Payam Pournazari, Meer-Taher Shabani-Rad, Jay Patel, Douglas A Stewart, Adnan Mansoor. University of Calgary/Calgary Laboratory Services (CLS), Calgary, AB, Canada; University of Calgary, Calgary, AB, Canada

Background: MCL is a lymphoid malignancy with t(11;14) (q13;q32) leading to the aberrant expression of cyclin-D1. MCL is believed to originate from naive B-cell. A subset of MCL with expression of germinal centre (GC) associated proteins (CD10/ BCL6) or post GC protein (MUM1) has been reported. MCL have also displayed mutated V(H) genes in some reports. Since, Germinal Centre associated B-cell (GCB) vs. activated B-cell (ACB) protein signature correlate with prognosis in Diffuse large B-cell lymphoma, we screened a cohort of MCL for a variety of specific GC associated proteins. We also compared GCB vs. ACB protein signature in MCL with independent known prognostic factor (Ki-67) to determine if any of GCB vs. ACB protein expression has any correlation with proliferation index or prognosis.
Design: WHO (2008) criteria were utilized for diagnosis (CD20/5/D1+). Triplicate cores (1mm) of FFPE diagnostic tissue were used to create tissue microarray (TMA). 4 micron thick sections were stained with monoclonal antibodies (CD10/Bcl6/MUM1/ LMO2/HGAL/Ki-67) according to standard protocol. Staining among >30% cells were scored positive, irrespective of staining intensity. High proliferation index was considered as Ki67 positivity among >30% neoplastic cells. Two paired student t test or Fisher exact tests was used for correlations with p<0.05 being considered significant.
Results: 62 pts (37-88 yrs, mean 62; median 59; M:F 4.6:1) were included. 7/62 (11%) showed GCB protein CD10 expression (Hans et al) while 38/62(62%) had ACB type (MUM1+) protein signature. Bcl6 positivity was noted only in 9/62 (14%); all of these patients were positive for MUM1 protein. None of the samples (0/62) were positive for LMO2 or HGAL. 36/62 (56%) had high Ki 67. Proliferation index did not correlate with GCB associated protein expression (p 0.987) or ACB (p 1.009) protein signature. MUM1 expression correlated well with Ki-67 expression (p=<0.0003); however, MUM1 expression did not imapct over all survival (p 0.178).
Conclusions: Our data indicate that CD10 and Bcl6 protein expression is seen in a subset of MCL but more specific GC markers (HGAL and LMO2) are not expressed in MCL. A significant proportion of MCL pts show expression of MUM1 protein, which is associated with high proliferation index. However, expression of MUM1 do not impact overall survival in MCL.
Category: Hematopathology

Monday, March 19, 2012 1:00 PM

Poster Session II # 194, Monday Afternoon


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