High-grade neuroendocrine tumors (HGNET) have distinctive tumor biology/behaviour. Newer modalities of treatment (immunotherapy) for them have been included in recent NCCN guidelines. Detection of programmed death receptor-ligand 1 (PD-L1) expression by immunohistochemistry have made easy identification of patients eligible for immunotherapy. We aimed to ascertain expression of PD-L1 on small cell and large cell neuroendocrine carcinomas of lung and review existing literature. Eighty-five cases of HGNET lung (primary/metastatic), were retrieved and reviewed. Immunostaining for PD-L1 using clone SP263 was done. Any amount/intensity of membranous staining of > = 1% tumor cells was cut-off for positivity. Previously published studies using Google and/Pubmed search engines were reviewed. Of 85 cases, 70 were small-cell lung cancer (SCLC), 11 large-cell neuroendocrine carcinoma (LCNEC) and 4 combined SCLC. Median age was 46.5 years with male preponderance. No PD-L1 expression was seen in 91.6% cases. The 7 positive cases were 4 LCNEC, 2 SCLC and 1 combined SCLC. The percentage positivity varied from 1–100%; lower percentage positivity was seen in SCLC. PD-L1 expression on immune cells was seen in 31.3% cases. Sixteen studies evaluating 1992 NET were found; E1L3N PD-L1 clone was commonly used clone. PD-L1 positivity was associated with better prognosis in most studies. There are only a few studies available in literature related to PDL1 expression in high grade neuroendocrine carcinomas of lung. In general, PD-L1 positivity is highly variable and seen in lower percentage of these tumors. With the recent approval of immunotherapy, biomarkers other than PD-L1 should also be investigated in these tumors.

高度神经内分泌肿瘤（HGNET）具有独特的肿瘤生物学/行为。最新的NCCN指南中已包含针对它们的较新的治疗方式（免疫疗法）。通过免疫组织化学检测程序性死亡受体-配体1（PD-L1）的表达，使容易鉴定符合免疫疗法的患者变得容易。我们旨在确定PD-L1在肺小细胞和大细胞神经内分泌癌中的表达，并复习现有文献。检索并审查了八十五例HGNET肺（原发/转移）病例。使用克隆SP263对PD-L1进行了免疫染色。截断≥1％肿瘤细胞的任何数量/强度的膜染色以求阳性。以前使用Google和// Pubmed发表的研究搜索引擎进行了审查。在85例病例中，有70例为小细胞肺癌（SCLC），11例大细胞神经内分泌癌（LCNEC）和4例合并SCLC。中位数年龄为46.5岁，男性占优势。在91.6％的病例中未观察到PD-L1表达。7例阳性病例为4例LCNEC，2例SCLC和1例合并SCLC。阳性百分比在1-100％之间；在SCLC中发现阳性率较低。在31.3％的病例中观察到免疫细胞上PD-L1的表达。发现了16个评估1992年NET的研究。E1L3N PD-L1克隆是常用克隆。在大多数研究中，PD-L1阳性与更好的预后相关。文献中只有很少的研究与肺高级神经内分泌癌中PDL1表达有关。通常，PD-L1阳性率变化很大，在这些肿瘤中的百分比较低。