Immunohistochemistry to investigate TBET, CMAF, GATA3, and PD1 expression. Photomicrographs (×40 objective, Olympus BX61 microscope) of representative examples (A) showing median expression of TH1-associated TBET (extreme left, black arrowhead showing TBET⁺ HRS cell) and TH2-associated CMAF (center left) and GATA3 (center right, black arrowhead showing GATA3⁺ HRS cell). PD1 expression was undetectable in most cases with the example (extreme right) being one of the few cases with >15 cells/high-power field associated with adverse outcome. Expression is weak compared with the internal positive control of tonsil (inset). Numbers of cells expressing each TH-associated marker and PD1 are compared (B) showing TH1-associated TBET is expressed by greater numbers of cells compared with TH2-associated CMAF/GATA3 and with minimal PD1 expression. DSS curves indicate a positive impact of TBET expression (C) and a negative impact of PD1 expression (D) in univariate analysis.