PD-L1 Assessment in Needle Core Biopsies of Non-Small Cell Lung Cancer: Interpathologist Agreement and Potential Associated Histopathological Features.

OBJECTIVE: Immune checkpoint inhibitors are used in the treatment of non-small cell lung cancer (NSCLC). Programmed cell death-ligand 1 (PD-L1) immunohistochemistry (IHC) assessed by pathologists is subject to interobserver variability. In advanced/metastatic disease and inoperable patients, PD-L1 assessment relies on biopsy specimens, commonly needle core biopsies (NCB). We aimed to determine the interobserver agreement for PD-L1 tumor proportion score (TPS) in NSCLC NCBs and identify histopathological features that may be related to interobserver variability. MATERIAL AND METHODS: Sixty NSCLC NCBs with PD-L1 IHC were evaluated independently by four pathologists from different institutions. PD-L1 TPS was evaluated in three categories: no/low expression ( < 1%), intermediate expression (1%49%), and high expression (≥50%). Histological tumor type, necrosis, tumor-infiltrating lymphocytes, tumor length/percentage in the biopsy, and crush/squeeze artifact was evaluated. RESULTS: The statistical analysis of the three PD-L1 TPS categories demonstrated moderate agreement (Fleiss Kappa 0.477) in the no/low category, fair agreement (Fleiss Kappa 0.390) in the intermediate category, and almost perfect agreement (Fleiss Kappa 0.952) in the high category. A significant correlation (p=0.003) was found between the crush/squeeze artifact in NCB and rate of discordant TPS categories. There was no significant correlation between pathologists' agreement in the TPS categories and histological tumor type, tumor length, tumor ratio, necrosis, and tumor-infiltrating lymphocytes. CONCLUSION: Our results demonstrated moderate agreement among pathologists for the PD-L1 TPS 1% cut-off in NSCLC NCB, which is lower than that reported in resection materials. The presence of crush/squeeze artifact in NCBs is significantly related to the rate of discordant TPS categories, suggesting that PD-L1 assessment of pulmonary NCBs requires an awareness of this artifact.

The Relationship of Pseudoangiomatous Stromal Hyperplasia (PASH)-Like Appearance in Invasive Breast Carcinomas with PASH Areas in Non-Tumoral Breast Parenchyma as Well as on Axillary Lymph Node Involvement.

Objectives: The aim of this study were to determine the relationship of pseudoangiomatous stromal hyperplasia (PASH)-like appearance in invasive breast carcinomas (IBCs) with PASH foci in the non-tumoral breast parenchyma as well as axillary lymph node involvement. Methods: In this study, 200 consecutive cases with IBC were re-examined. Cases with and without PASH-like appearance in IBC were determined. Each case was assessed regarding the presence of accompanying PASH foci (CD34+, CD31-) in the non-tumoral areas in addition to other clinicopathological parameters. Results: PASH-like appearance within the IBC was present in 22 of the 200 cases (11%) and absent in 178 (89%). The presence of PASH foci in the non-tumoral breast parenchyma was significantly more common in IBC with PASH-like appearance compared to the group without such areas. However, there was no significant difference between the groups regarding other clinicopathological parameters (age, tumor size, nuclear and histological grade, Estrogen receptor/Progesterone receptor status, HER2 status, and Ki-67 proliferation index), lymphovascular invasion (LVI), and axillary lymph node involvement. There was no significant difference between the two groups regarding the histopathological findings observed in the non-tumoral areas. Conclusion: PASH-like appearance within IBC was found to be associated with higher rate of PASH foci in the non-tumoral breast parenchyma. However, such cases do not show a difference as regards LVI and axillary lymph node metastasis.