Selected IHC panel included in the diagnostic algorithm. (A) Positive immunostains for GATA3 (nuclear) and its corresponding target protein CCR4 (membranous) in a PTCL-GATA3 case. This case is negative for TBX21 and CXCR3. (B) Positive immunostains for TBX21 (nuclear) and its target protein CXCR3 (membranous) in a PTCL-TBX21 case. This case is negative for GATA3 and CCR4. (A-B) Original magnification ×600.