[1226] MNDA, a New Marker Useful in the Recognition of Nodal Marginal Zone Lymphoma and Its Differential with Follicular Lymphoma

G Kanellis, G Roncador, S Montes-Moreno, A Arribas, M Mollejo, Y Campos-Martin, M Piris. CNIO, Madrid, Spain

Background: Specific immunohistochemistry markers for NMZL are not known, and those of FL (CD10, BCL6) not always conclusive. We tried to clarify this grey area of differential diagnosis by using the novel marker Myeloid Nuclear Differentiation Antigen (MNDA), developed by the Monoclonal Antibody Unit of our Centre, as suggested by a previous expression profiling study.
Design: Gene expression profile studies were performed in a series of small B cell lymphoma cases.Differentially expressed genes among small B cell lymphoma subtypes were identified by paired comparison using t-test analysis.A new monoclonal antibody against MNDA protein was generated and immunohistochemical characterization of a series of 464 B- cell Non-Hodgkin Lymphoma cases was performed.
Results: Gene expression profile identifies MNDA as a component of NMZL signature. A MoAb recognizing MNDA was prepared and validated through Western Blotting and transfected cell lines. MNDA expression is nuclear and, in reactive lymph nodes, was seen by mature granulocytes and monocytes with great intensity. With a lesser intensity the MNDA expression was found within the B cells of the hyperplastic IgD-negative marginal zone, but not seen by monocytoid B cell, and especially not by germinal centre cells(GC). The analysis of a series of 464 B cell NHL showed a heterogeneous expression of MNDA (Table 1). Of greater interest is the expression of MNDA among NMZLs and FLs. The former showed 76% (41/54) positivity and an expression pattern that was marginal, or marginal with interfollicular constituent. MNDA positivity in GC was observed in cases of follicular colonization. In contrast, only 5% of FL cases expressed MNDA (10/183) with an intrafollicular staining intensity which appeared less intense than the one seen in the rim of the neoplastic follicules.


Conclusions: MNDA is a potentially useful marker in the recognition of normal marginal zone cells and the diagnosis of NMZL cases, with a limited expression among FL. which can offer potential value in the analysis of normal B-cell subpopulations and the differential between NMZL and FL.
Category: Hematopathology

Tuesday, March 10, 2009 9:30 AM

Poster Session III # 133, Tuesday Morning