Higher MHC-II expression in tumor cells was associated with the absence of lymphovascular invasion (p = 0.042); larger amounts of TILs (p < 0.001); frequent formations of tertiary lymphoid structures (p < 0.001); higher expression of myxovirus resistance gene A, one of the main mediators of the interferon signaling pathway (p < 0.001); and higher expression of double-stranded RNA-activated protein kinase, which can be induced by interferons (p = 0.008).
These results suggest that follicular cells newly express PKR during thyroid carcinogenesis, that PKR is more expressed in papillary carcinoma than in nonpapillary carcinoma, that PKR expression may be associated with high vascular invasion and satellite nodules, and that PKR expression is linked to low cell proliferative activity.