The Reproducibility of the Immunohistochemical PD-L1 Testing in Non-Small-Cell Lung Cancer: A Multicentric Italian Experience

Figure 2

(a) Inappropriate evaluation of immune cells (macrophages) in crushed TMA cores may be a source of error (case 8; gold-standard score 1, wrongly scored as 2). (b) In particular, challenging cases the average threshold of positive tumor cell cells may be wrongly assigned (i.e., 40 versus 60%). (c) In cases (like n.17) with low-intense and focal reactivity only the evaluation at high-power field (40x) may assign correctly as intermediate expressor the tumor, differentiating immune and neoplastic cells. (d) If a TMA core is sampled at the periphery of the main tumor nodule, where only occasional embolic aggregates are present, they may be disregarded by a not accurate pathological examination (case n.12).

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