Immunohistochemistry showed B-cell lymphoma antigen (Bcl) 2(+), Bcl-6(+), cluster of differentiation (CD) 3(+), CD5(+), CD10(+), CD20(+), CD21 (follicular dendritic cells {FDC}+), CD23(+), cyclin D1(-), Ki-67 (index 3%), SRY-box transcription factor 11 (SOX11)(-), CD19(+), and lymphoid enhancer-binding factor 1 (LEF-1)(-), which supported a diagnosis of MALT lymphoma. This evidence concerns the gene LEF1 and MALT lymphoma.