Endocrine Abstracts

Introduction: CYP11B2 is a key enzyme of primary aldosteronism, and several factors are involved in the regulation of CYP11B2 expression and the overproduction of aldosterone. Somatic mutations in aldosterone-driver genes are strongly associated with CYP11B2 expression and have been only detected in the CYP11B2-positive tumor area, indicating that aldosterone producing adenoma (APA) intratumoral heterogeneity corresponds to non-uniform CYP11B2 expression in neoplastic cells. In addition, CYP11B2 can contribute to the clinical diagnosis of primary aldosteronism. CYP11B2 has the potential to synthesize hybrid steroids, which is a unique and characteristic behavior of APA that is distinctive from bilateral hyperaldosteronism (BHA). However, the pathophysiology of primary aldosteronism in both APA and non-neoplastic subtypes remains controversial.

Objective: To assess the functional heterogeneity of adrenal tumors in primary aldosteronism

Material and methods: Retrospective evaluation adrenal tumors from patients with primary aldosteronism (n=20). According to CT unilateral macrohyperplasia was detected in 19 patients (95% of total), all of them were confirmed to have unilateral hyperproduction of aldosterone according to AVS. Selected tumors were stained with anty-CYP11B2 antibody.We evaluated the CYP11B2 expression in the adenoma and in the adjacent adrenal cortex.

Results: Immunohistochemistry studies of the resected adrenals from 20 patients with PA operated due to unilateral production of aldosterone using CYP11B2 staining showed that 10 of those with an adenoma on CT scanning showed CYP11B2 staining in the adenoma. Furthermore, 5 cases of an unilateral adenoma, showed CYP11B2 staining in the adjacent adrenal cortex and an absence of staining for CYP11B2 in the adenoma. 5 cases showed CYP11B2 expression is heterogeneously immunolocalized throughout the tumor area.

Conclusions: Thus, the functional heterogeneity of adrenal tumors in primary aldosteronism has been proven. It is necessary to compare the data of immunohistochemical studies on the expression of CYP11B2 with the indicators of the level of 18-hydroxycortisol, 18-oxocortisol.