BCL6 and MALT lymphoma: Immunohistochemically, FL typically shows positivity for CD10, CD20, CD21, BCL2, and BCL6, and negativity for CD3.11) By contrast, MALT lymphoma generally lacks follicular architecture and is negative for CD10 and BCL6, often exhibiting lymphoepithelial lesions and plasmacytic differentiation.11) DLBCL is usually characterized by a diffuse architecture, marked cytologic atypia, and a high Ki-67 proliferation index; however, rare cases of high-grade transformation from FL require careful histologic grading and Ki-67 evaluation.11)