Immunohistochemistry on tissue sections of HL. Representative photomicrographs of positive immunohistochemistry staining on tissue sections for 16 proteins: ALCAM, cathepsin C, cathepsin S, CD44, CD63, fractalkine, IL25, IP-10, MIF, RANTES, and TARC on paraffin-embedded tissues; CD100, CD150, CD26, CD71, and IL1R2 on frozen sections. Photomicrographs were taken using Aperio ScanScope System and were acquired with Digital Slide Information Management Software (Aperio Technologies, Vista, CA). Image layout was subsequently processed by Microsoft Office XP PowerPoint (Microsoft, Seattle, WA; original magnification, ×400). Arrows mark a few of the positive typical HRS cells in all cases.