Abstract

Background: Primary aldosteronism (PA), characterized by autonomous aldosterone hypersecrection from adrenal glands, has emerged as the leading endocrine etiology of secondary hypertension in Vietnam. The diagnosis of PA relies on the Primary Aldosteronism Histopathology Classification System (HISTALDO), which was ratified in the 2022 WHO Classification of Endocrine and Neuroendocrine Tumors. This system integrates H&E morphological examination with functional immunohistochemistry (IHC) evaluting CYP11B2 expression (aldosterone synthase) – the terminal enzyme in the biosynthesis of aldosterone. Objectives: Standardization of CYP11B2 immunohistochemistry protocol in primary aldosteronism-related adrenocortical tumors. Materials and Methods: The study established and standardized the immunohistochemical (IHC) staining protocol for CYP11B2 on 34 formalin-fixed paraffin-embedded (FFPE) blocks obtained from the patients diagnosed with aldosterone-producing adrenocortical tumors at the University Medical Center Ho Chi Minh City between January 1, 2024, and December 31, 2024. Results: The study successfully established and standardized the immunohistochemical (IHC) staining protocol to determine CYP11B2 protein expression in adrenal cortical glands, providing direct histopathological evidence of physiological aldosterone secretion. Conclusion: The successful standardization of the CYP11B2 IHC protocol establishes a critical baseline for definitive diagnosis and future routine clinical implementation. The distinct immunophenotypic heterogeneity of CYP11B2 highlights diverse hormone secretion patterns, underscoring its essential role in accurate patient stratification and the optimization of individualized therapeutic strategies.