Primary aldosteronism with aldosterone-producing adenoma consisting of pure zona glomerulosa-type cells in a pregnant woman.

Aldosterone-producing adenoma (APA) consisting of pure zona glomerulosa (ZG)-type cells is extremely rare, and primary aldosteronism complicated by pregnancy is also rare. We report a case of APA discovered in a 32-year-old pregnant woman who visited our hospital for hypertension and hypokalemia at 26 weeks gestation. Elevated plasma aldosterone concentration and hypokalemia were observed, and an magnetic resonance imaging scan demonstrated a right adrenal mass. A laparoscopic adrenalectomy was performed because of refractory hypokalemia. Pathologically, the adrenal mass was diagnosed as APA, and in addition to the cytological features, in situ hybridization and real-time polymerase chain reaction proved that all the component cells were ZG-type cells. The cells also showed estrogen receptor beta immunoreactivity and melanocortin 2 receptor mRNA expression, suggesting that estrogen and/or ACTH might be related to the proliferation of APA cells during pregnancy. Our case is the first report of APA consisting of ZG-type cells discovered during pregnancy.