IRF4 and marginal zone lymphoma: In a diagnostic setting, the main histological differential diagnoses are florid follicular hyperplasia (FFH) (given the expanded GCs and lack of strong BCL2 expression), pediatric marginal zone lymphoma (PMZL) which shows morphological and clinical similarities, t(14;18)− FL where the age at presentation may overlap, and LBCL with IRF4 rearrangements.