There was a higher M2:M1 ratio in cluster 1 (SDHx, VHL, FH, n = 27) tumours compared to cluster 2 (RET, n = 6) (P = 0.017) and a lower proportion of CD8 cytotoxic (Tc) lymphocytes in PPGLs with a known genetic diagnosis (P = 0.047). The gene discussed is CD8A; the disease is neoplasm.