H&E and OCT4/CD34 for the assessment of lympho-vascular invasion in seminoma and embryonal carcinoma.

BACKGROUND: Lymphovascular invasion (LVI) is a relevant prognostic factor in germ cell tumors of the testis (GCTT), and it is included in the pT stage. However, its detection on hematoxylin and eosin (H&E) slides is very challenging, and previous studies reported fair to moderate inter-observer agreement among dedicated uropathologists. In the present study, we tested H&E and a recently developed in-house double staining for OCT4/CD34 to detect LVI in GCTT. METHODS: Nine authors [5 non-uropathologists and 4 uropathologists] independently evaluated 34 consecutive and retrospectively enrolled cases of GCTT. We assessed the inter-observer agreement (Fleiss's Kappa) with both H&E and OCT4/CD34. Besides, we compared the consensus diagnosis on both H&E and OCT4/CD34-stained sections with the original diagnosis to evaluate the pT re-staging (McNemar test) and identify the sources of disagreement. RESULTS: The inter-observer agreement among uropathologists plus non-uropathologists was fair with both H&E (KF=0.398; p < 0.001) and OCT4/CD34 (KF=0.312; p < 0.001). OCT4/CD34 (KF=0.290; p < 0.001) slightly reduces the inter-observer agreement compared to H&E (KF=0.321; p < 0.001) for non-uropathologists; in contrast, OCT4/CD34 (KF=0.293; p < 0.001) significantly reduces the inter-observer agreement compared to H&E (KF=0.529; p < 0.001) for uropathologists, changing it from moderate to fair. Consensus diagnosis with H&E modified the LVI status of the original diagnosis in 8/34 (23.5 %) cases (p: 0.070), with pT re-staging in 2/34 (5.9 %) cases (p: 0.500). Consensus diagnosis with OCT4/CD34 modified the LVI status of the original diagnosis in 8/34 (23.5 %) cases (p: 0.289), with pT re-staging in 3/34 (8.8 %) cases (p: 0.250). The consensus diagnosis with OCT4/CD34 modified the consensus diagnosis with H&E in 8/34 (23.5 %) cases (p: 0.727), and these findings resulted in pT-restaging in 3/34 (8.8 %) cases (p: 0.500). The sources of disagreement among uropathologists were: H&E [artefactual clefts misinterpreted as LVI in 4/6 (66.7 %) cases and true foci of LVI misinterpreted as clusters of histiocytes within the vessels in 2/6 (33.3 %) cases], OCT4/CD34 [artefactual clefts misinterpreted as LVI in 2/8 (25 %) cases, true LVI misinterpreted as artefactual clefts in 2/8 (25 %) cases or floaters in 4/8 (50 %) cases]. CONCLUSIONS: OCT4/CD34 does not improve the inter-observer agreement for the assessment of LVI in OCT4(+) GCTT. Consensus diagnosis with H&E modifies the LVI status in a significant number of cases, resulting in changes of the pT stage in a relatively small subgroup. Consensus diagnosis with OCT4/CD34 provides little additional benefit since it cannot exclude mimickers of LVI such as floaters and artefactual clefts. These results argue against the adoption of this diagnostic tool for the routine assessment of OCT4(+) GCTT.

Interobserver agreement of PD-L1 (SP263) assessment in advanced NSCLC on cytological smears and histological samples.

BACKGROUND: The PD-L1 assessment is mandatory for the selection of patients affected by advanced non-small-cell lung cancer (NSCLC) who can benefit from the PD-1/PD-L1 checkpoint inhibitors therapy. Previous studies tested PD-L1 on cytological smears to evaluate this sample as an alternative to formalin-fixed paraffin-embedded (FFPE) ones, but several critical issues needed to be clarified. AIM: We evaluated the cyto-histological agreement (CHA) and the PD-L1 interobserver agreement (IrOA) among three different pathologists (Path1, Path2, Path3) on 160 paired cytological smears and histological samples of advanced NSCLC. RESULTS: With the cut-off of < 50%/≥ 50%, CHA resulted good for Path1 (Cohen's k: 0.702) and Path3 (Cohen's k: 0.731), moderate for Path2 (Cohen's k: 0.576) adopting the same cut-off, the IrOA was moderate (ICC 0.72 [95% CI: 0.63-0.78]) for smears and good for histological samples (ICC 0.85 [95% CI: 0.80-0.85]). CONCLUSION: With a cut-off system of < 50%/≥ 50%, PD-L1 assessment shows moderate to good CHA and exhibited moderate IrOA on smears and good IrOA on FFPE. As result, PD-L1 assessment should be improved on cytological smears as well as could be a suitable alternative for patients without FFPE samples and not eligible for pembrolizumab, adopting a cut-off of < 50%/≥ 50%; presumably, an appropriate pathologist training could further improve the reproducibility.