Update on primary bilateral macronodular adrenal hyperplasia (PBMAH)

Primary bilateral macronodular adrenal hyperplasia (PBMAH), characterized by bilateral benign adrenal macronodules (>1 cm) potentially responsible for variable levels of cortisol excess, is a rare and heterogeneous disease. However, its frequency increases due to incidentally diagnosed cases on abdominal imaging carried out for reasons other than suspected adrenal disease. Mostly isolated, it can also be associated with dominantly inherited genetic conditions in rare cases. Considering the bilateral nature of adrenal involvement and the description of familial cases, the search of a genetic predisposition has led to the identification of germline heterozygous inactivating mutations of the putative tumor suppressor gene ARMC5, causing around 25% of the apparent sporadic cases. Rigorous biochemical and imaging assessment are key elements in the management of this challenging disease in terms of diagnosis. Treatment is reserved for symptomatic patients with overt or subclinical Cushing syndrome, and was historically based on bilateral adrenalectomy, which nowadays tends to be replaced by unilateral adrenalectomy or lifelong treatment with cortisol synthesis inhibitors.