Follicular lymphoma, grade 1/3, CD10 stain on paraffin-embedded section. There are CD10+ cells present in this diffuse area. CD10 is not normally found on interfollicular B cells; thus its expression outside of follicles is suspicious for follicular lymphoma. In this setting, CD10 expression is useful for distinguishing follicular lymphoma from a reactive process, and also in distinguishing it from other small B-cell lymphomas.