Nanba, Kazutaka

Abstract Objective Recent studies suggest a unique disease profile in elderly patients with primary aldosteronism (PA), who have a high prevalence of comorbidities and low clinical cure rate post-adrenalectomy. This study aims to investigate histopathology and genetic characteristics of PA in late adulthood. Methods Formalin-fixed, paraffin-embedded adrenal tissue sections from 114 patients with PA who underwent unilateral adrenalectomy at age 60 or older were used. Aldosterone synthase (CYP11B2) immunohistochemistry (IHC) was performed for histopathologic analysis. Somatic DNA variants were identified in aldosterone-producing tissue following CYP11B2 IHC-guided sequencing. Results Histopathologic analysis revealed that 56 adrenals contained an aldosterone-producing nodule (APN) (49%), 44 contained an aldosterone-producing adenoma (APA) (39%), 7 contained multiple APN (6%), and 7 contained only non-functioning adenomas [NFA, of which 6 had at least one aldosterone-producing micronodule (APM) in the adjacent tissue] (6%). NFAs were also identified alongside APN/APA in 24 cases. An APN was the most common histologic subtype in men (51/88, 58%), while APA was predominant in women (18/26, 69%). Of 67 APNs with successful sequencing, the majority had variants in CACNA1D (40/67, 60%). KCNJ5 variants were the most common alteration in APA (14/44, 32%). Conclusions Older individuals with lateralized PA exhibit distinct genetic and histologic causes of disease with sex differences in mutation prevalence and adrenal histopathology. In APN, the most frequently altered gene is CACNA1D, while KCNJ5 variants are most common in APA. Unlike young patients with PA, the presence of NFA is a frequent observation in late adulthood individuals with PA.

Abstract Context Due to its rare incidence, molecular features of primary aldosteronism (PA) in young adults are largely unknown. Recently developed targeted mutational analysis identified aldosterone-driver somatic mutations in aldosterone-producing lesions, including aldosterone-producing adenomas (APAs), aldosterone-producing nodules (APNs), and aldosterone-producing micronodules, formerly known as aldosterone-producing cell clusters. Objective To investigate histologic and genetic characteristics of lateralized PA in young adults. Methods Formalin-fixed, paraffin-embedded adrenal tissue sections from 74 young patients with lateralized PA (<35 years old) were used for this study. Immunohistochemistry (IHC) for aldosterone synthase (CYP11B2) was performed to define the histopathologic diagnosis. Somatic mutations in aldosterone-producing lesions were further determined by CYP11B2 IHC-guided DNA sequencing. Results Based on the CYP11B2 IHC results, histopathologic classification was made as follows: 48 APAs, 20 APNs, 2 multiple aldosterone-producing nodules (MAPN), 1 double APN, 1 APA with MAPN, and 2 nonfunctioning adenomas (NFAs). Of 45 APAs with successful sequencing, 43 (96%) had somatic mutations, with KCNJ5 mutations being the most common genetic cause of young-onset APA (35/45, 78%). Of 18 APNs with successful sequencing, all of them harbored somatic mutations, with CACNA1D mutations being the most frequent genetic alteration in young-onset APN (8/18, 44%). Multiple CYP11B2-expressing lesions in patients with MAPN showed several aldosterone-driver mutations. No somatic mutations were identified in NFAs. Conclusion APA is the most common histologic feature of lateralized PA in young adults. Somatic KCNJ5 mutations are common in APAs, whereas CACNA1D mutations are often seen in APNs in this young PA population.