Significance of fascin actin-bundling protein 1, programmed death-ligand 1, and cluster of differentiation 8+ tumor infiltrating lymphocytes in primary adrenocortical tumors: an immunohistochemical study

Adrenal cortical adenomas are common benign tumors, making up 40.48% of suprarenal lesions in Egypt, while adrenocortical carcinoma (ACC) is a rare yet aggressive malignancy with a global prevalence of 4–12 cases per million and a 5-year survival rate of 16–38%. Immune checkpoint molecule programmed death-ligand 1 (PD-L1) aids cancer immune evasion by suppressing T-cell responses, while fascin actin-bundling protein 1 (FSCN1), an action-bundling protein, promotes cell migration and tumor metastasis. Cluster of differentiation 8 + (CD8 + ) T cells, key players in antitumor immunity, target malignant cells, with their tumor infiltration being essential for effective immune responses against cancer. This study’s objective is to estimate PD-L1 and FSCN1 immunohistochemical expression in adrenocortical tumors, correlating them with CD8 + tumor-infiltrating lymphocytes (TILs) and histopathological features. The goal is to explore their roles in tumor progression, prognosis prediction, and survival outcomes. Patient and methods This retrospective study evaluates the immunohistochemical expression of PD-L1, CD8, and FSCN1 markers in cases of adrenocortical adenoma and carcinoma. Immunohistochemical staining was conducted using the standard labelled streptavidin-biotin method, with the findings analyzed about clinicopathological parameters. Results This study of 60 of adrenocortical adenomas and carcinomas found significant differences in age, tumor size, PD-L1, and FSCN1 expression, with higher levels in carcinomas. PD-L1 correlated with advanced stage and metastasis, while FSCN1 correlated with capsular and lymphovascular invasion in carcinoma cases. CD8 + TIL density showed no statistical differences but correlated with poor survival outcomes in carcinomas. Conclusion Its potential as a prognostic marker and therapeutic target is highlighted by the correlations found between greater PD-L1 expression and advanced stage, metastasis, and poor prognosis in ACC. Elevated FSCN1, linked to invasion and metastasis, shows superior diagnostic accuracy (86.7%) over PD-L1. Paradoxically, higher CD8 + TIL density associates with poor survival, likely due to immune dysfunction in the tumor microenvironment.