睾丸生殖细胞肿瘤的自发消退是众所周知的现象。然而，自发消退的确切机制仍不清楚。我们的研究旨在调查自发消退的睾丸生殖细胞肿瘤中程序性死亡配体 1 (PD-L1) 的表达，探索免疫反应与自发消退之间的联系。从 356 个睾丸生殖细胞肿瘤样本中，我们挑选出 5 个完全消退的肿瘤和 6 个部分消退的肿瘤。在部分消退的六例中，有四例发现了残留的精原细胞瘤成分，而在其余两例中，发现了胚胎癌成分。对 20 例纯精原细胞瘤和 20 例混合生殖细胞肿瘤 (MGCT) 进行了比较。对肿瘤细胞和瘤内/瘤周淋巴细胞中的 PD-L1 表达进行半定量免疫组织化学分析。完全消退的肿瘤中没有 PD-L1 表达。所有部分消退的肿瘤均显示肿瘤残余物内/瘤周淋巴细胞中的表达。与 MGCT 相比，纯精原细胞瘤中的表达频率明显更高 (P = 0.004)。精原细胞瘤成分与 PD-L1 阳性淋巴细胞比例呈正相关，Kendall's Tau-b 系数为 0.626（P < 0.001）。肿瘤细胞在胚胎癌成分内的三个 MGCT 中显示出 PD-L1 表达。我们的结果支持肿瘤自发消退的免疫学机制，在含有精原细胞瘤成分的睾丸肿瘤中具有最强的潜力。然而，还需要进一步的研究来更精确地确定PD-L1配体在自发消退的肿瘤微环境中的作用。

Spontaneous regression of testicular germ cell tumors is a well-known phenomenon; however, the precise mechanisms of spontaneous regression are still unknown. Our study aimed to investigate programmed death-ligand 1 (PD-L1) expression in spontaneously regressed testicular germ cell tumors, exploring the link between the immune response and spontaneous regression. From a sample of 356 testicular germ cell tumors, we singled out 5 completely regressed and 6 partially regressed tumors. In four out of six cases with partial regression, a residual seminoma component was found, while in the remaining two cases, an embryonal carcinoma component was found. Comparisons were made with 20 pure seminomas and 20 mixed germ cell tumors (MGCTs). A semiquantitative immunohistochemical analysis of PD-L1 expression in tumor cells and intra/peritumoral lymphocytes was performed. There was no PD-L1 expression in tumors with complete regression. All partially regressed tumors showed expression in intra/peritumoral lymphocytes within the tumor remnants. Expression was significantly more frequent in pure seminomas compared to MGCTs (P = 0.004). A positive correlation was demonstrated between the seminoma component and the proportion of PD-L1 positive lymphocytes, with a Kendall's Tau-b coefficient of 0.626 (P < 0.001). Tumor cells showed PD-L1 expression in three MGCTs within the embryonal carcinoma component. Our results support an immunological mechanism of spontaneous tumor regression, with the strongest potential in testicular tumors containing seminoma components. However, further research is necessary to determine the role of PD-L1 ligand more precisely in the microenvironment of spontaneously regressed tumors.