[1354] MNDA but Not MUM1 Is a Useful Marker for Nodal Marginal Zone Lymphoma To Differentiate from Follicular Lymphoma

Calvin K Chen, Zhicheng Mo, Serhan Alkan. Cedars-Sinai Medical Center, Los Angeles, CA

Background: Myeloid cell nuclear differentiation antigen (MNDA) is expressed by myeloid cells, including monocytes, granulocytes and subsets of B-cell lymphomas. MNDA is expressed in marginal zone B cells in normal lymph node, but not in reactive monocytoid B cells. On other hand, the expression of multiple myeloma oncogene-1 (MUM-1), a member of IRF family of transcription factor, is thought to be infrequently expressed in low grade follicular lymphoma (FL) but could be observed in some marginal zone lymphomas (MZL). Distinguishing MZL from FL can often post a diagnostic dilemma. To investigate the potential utilization with MNDA and MUM-1 to aid the diagnostic assessment of MZL and FL, we assessed expression of MNDA and MUM-1 in these entities.
Design: Whole tissue sections from nodal MZL (10 cases) and FL (12 cases) were initially analyzed by multiple markers (CD5, CD20, BCL-2, BCL6, cyclin D1) and FISH probes against BCL-2 for diagnosis of MZL and FL. Immunohistochemistry for MNDA and MUM-1 were performed using a heat-induced epitope retrieval technique. MNDA is determined as positive if nuclear staining on the lymphoma cells were greater than 30% of cells. The MUM-1 positivity was scored as negative, weak and strong staining.
Results: 8/10 (80%) of nodal MZL cases showed strong nuclear expression of MNDA in the lymphoma cells while only 1/12 (8.3%) of FL had expression of this marker. MUM-1 expression was not informative as it showed strong expression in plasma cells and occasionally in the perinodular zones of both lymphomas. Weak expression of MUM-1 was noted in 6/12 (50%) of nodal MZL and 2/10 (20%) of FL as shown in the table.

 FLNodal MZLp-value
MNDA1/12 = 8.33%8/10 = 80%0.001
Weak staining by MUM-12/10 = 20%6/12 = 50%0.145

Conclusions: Currently there is no specific marker for diagnosis of MZL as it is often requires exclusion of other low grade lymphomas. Differentiating FL from nodal MZL is usually straight forward; however, colonization by nodal MZL, or patchy interfollicular involvement by FL can sometimes post a diagnostic difficulty. In our study, MNDA appears to show preferential staining in nodal MZL than FL. While weaker staining intensity by MUM-1 was observed more frequently in nodal MZL than in FL, it lacks statistical significance. In conclusion, MNDA, but not MUM-1, appears to be a useful marker for differentiating nodal MZL from FL.
Category: Hematopathology

Tuesday, March 5, 2013 1:00 PM

Poster Session IV # 255, Tuesday Afternoon


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