CAV1.3, HSD3B2 and CYP11B2 immunoexpressions in aldosterone-producing adenoma are not correlated with post-adrenalectomy outcome in primary aldosteronism

Somatic mutations of KCNJ5, ATP1A1, CACNA1D, ATP2B3, have been shown to be involved in the pathophysiology of aldosterone-producing adenoma (APA). This study aimed to investigate immunolocalization of CaV1.3 coded by CACNA1D, as well as steroidogenic enzymes HSD3B2 and CYP11B2 (rate-limiting enzyme for aldosterone production) in paraffin-embedded APA tissues and to relate these findings to mutation status, histopathology and outcome following adrenalectomy. APA tissues were divided into subgroups based on their different somatic mutations. Size and cell composition of tumors, immunolocalization and semi-quantitative expression of CYP11B2, HSD3B2 and CaV1.3 were analyzed. Scoring staining intensity was determined along with clinical findings. Our results showed that a majority of APA consist of both zona fasciculata-like and zona glomerulosa (ZG)-like cells. CACNA1D-mutated APA were significantly smaller than KCNJ5-mutated (P < 0.05). APA with a somatic mutation presented CYP11B2 positive clusters or scattered cells with variable degree of staining while non-mutated APA were weakly stained for CYP11B2 or presented only clusters in adjacent ZG. H-Score for CYP11B2 even when adjusted for tumor size, was significantly different between non-mutated and KCNJ5-mutated APA (P < 0.05). Immunoreactivity of CaV1.3 and HSD3B2 was present in all APA tissues analyzed. Potassium levels of all patients were normalized after adrenalectomy. Better clinical outcome only correlated with aldosterone renin ratio at diagnosis and shorter duration of presurgical hypertension. Our findings suggest that KCNJ5 and not ATP1A1, CACNA1D or ATP2B3 mutated APA present a significantly different CYP11B2 immunoreactivity, compared with non-mutated APA. However immunoreactivities of CYP11B2, CaV1.3 or HSD3B2 are not correlated with outcome.