Follicular lymphoma, grade 1/3, CD20 (pan-B cell) immunoperoxidase stain, paraffin-embedded section. The follicles are strongly positive, and many positive cells are also seen between the follicles. Reactive follicles would also be CD20+, but numerous CD20+ B cells are not normally seen in the interfollicular region. The interfollicular region is commonly involved by follicular lymphoma.