In this study, we aimed to clarify the extent of AID expression in ocular adnexal IgG4+ MZL and IgG4-ROD compared with MZL without IgG4-positive cells of ocular adnexa (IgG4- MZL) to see if AID plays a role in the pathogenesis of IgG4+ MZL while describing the histopathological characteristics of ocular adnexal IgG4+ and IgG4- MZL compared with those of IgG4-ROD. Here, AICDA is linked to marginal zone lymphoma.