CD274 and neoplasm: SP142, in particular, has shown significantly lower sensitivity in PD-L1 tumor cell staining, which may partially explain the lowest PD-L1 positivity rate (6.1%) reported in PTC by Ahn et al. [19,29], further compounded by their use of tissue microarrays, instead of whole tissues, that may underestimate intratumoral heterogeneity [29]. Interpretation in terms of subcellular localization further complicates PD-L1 assessment, with higher expression rates being reported when cytoplasmic, rather than membranous, staining is considered positive.