ADRENAL CORTEX AND MEDULLA: Edited by Irina BancosUpdate on primary micronodular bilateral adrenocortical diseasesMaillet, Michel; Bourdeau, Isabelle; Lacroix, AndréAuthor Information Division of Endocrinology, Department of Medicine, Centre de Recherche du Centre hospitalier de l’Université de Montréal (CHUM), Université de Montréal, Québec, Canada Correspondence to André Lacroix, MD, FCAHS, Division of Endocrinology, Department of Medicine, Research Center, CHUM, 3840 Saint-Urbain Street, Montréal, QC, Canada H2W 1T8. Tel: +1 514 890 8000 x30998; fax: +1 514 412 7128; e-mail: firstname.lastname@example.org Current Opinion in Endocrinology & Diabetes and Obesity: June 2020 - Volume 27 - Issue 3 - p 132-139 doi: 10.1097/MED.0000000000000538 Buy Metrics Abstract Purpose of review Primary micronodular bilateral adrenocortical hyperplasias (MiBAH) are rare challenging diseases. Important progress in understanding its pathophysiology and genetics occurred in the last two decades. We summarize those progress and recent data on investigation and therapy of MiBAH focusing on primary pigmented nodular adrenocortical disease (PPNAD). Recent findings Larger recent cohorts of PPNAD patients from various countries have confirmed their variable Cushing's syndrome phenotypes. Age of onset is earlier than other ACTH-independent Cushing's syndrome causes and the youngest case have now occurred at 15 months. Two retrospective studies identified an increased risk of osteoporotic fractures in PPNAD as compared with other Cushing's syndrome causes. The utility of 6-day oral dexamethasone test to produce a paradoxical increase of urinary-free cortisol in PPNAD was confirmed but the mean fold of increase was of 48%, less than previously suggested. Several new genetic variants of the PRKAR1A gene have been reported in PPNAD or Carney complex (CNC). Remission of Cushing's syndrome with unilateral adrenalectomy was reported in a few patients with PPNAD. Summary MiBAH, PPNAD and CNC are rare challenging diseases, but with combined expert clinical and genetic approaches a comprehensive investigation and prevention strategy can be offered to affected patients and families. Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.