Immune receptor translocation-associated protein 1 and myeloid nuclear differentiation antigen are useful markers for the differential diagnosis of marginal zone lymphoma.

This study aimed to assess the potential diagnostic utility of immune receptor translocation-associated protein 1 (IRTA1) and myeloid nuclear differentiation antigen (MNDA) expression in marginal zone lymphoma (MZL). We evaluated whole-tissue sections from 686 specimens; specifically, reactive lymphoid hyperplasia (n=60), MZL (n=284), follicular lymphoma (n=156), mantle cell lymphoma (n=64), chronic lymphocytic leukaemia/small lymphocytic lymphoma (n=51), lymphoplasmacytic lymphoma (n=17), and diffuse large B-cell lymphoma (DLBCL; n=54). Immunohistochemical staining for IRTA1, MNDA, and other markers (CD10, BCL-6, CD5, CD23, cyclin D1, SOX-11, and LEF-1) was performed using an automated system. IRTA1 was expressed in 62.3% (177/284) of MZL vs 8.7% (25/288) of other small B-cell lymphoma and 14.81% (8/54) of DLBCL specimens (p<0.001 and p<0.001, respectively). MNDA was expressed in 60.9% (173/284) of MZL vs 24.7% (71/288) of other small B-cell lymphoma and 25.93% (14/54) DLBCL specimens (p<0.001 and p<0.001, respectively). Expression of IRTA1 had a higher specificity than MNDA for MZL. Expression of either IRTA1+ or MNDA+ was detected in 78.9% (224/284) of MZL specimens, whereas coexpression was less common (44.4%, 126/284). Within MZL subtypes, IRTA1 and MNDA were expressed at lower frequencies in nodal MZL (55.7% and 55.7%, respectively) than in mucosa-associated lymphoid tissue lymphoma (64.1% and 62.7%, respectively). Expression of IRTA1 alone, or either IRTA1+ or MNDA+, was less frequent among MZL with plasma cell differentiation than among MZL with classical cell morphology (p=0.063 and 0.071, respectively), albeit not significantly. IRTA1 and MNDA are sensitive and specific markers for the differential diagnosis of MZL, and they may be helpful in distinguishing MZL from histologic mimics.