FCRL4 and MALT lymphoma: FcRL4 is an immunoregulatory receptor, selectively expressed by B cells with a marginal zone phenotype localized in the subepithelial regions and within the epithelium of tonsils and Peyer patches (marginal zone equivalents) [75,76] Neoplastic B-cells-associated MALT lymphomas, especially those involved in LELs, have been shown to express FcRL4 [76].