Adrenal Medullary Hyperplasia: A Systematic Review and Meta-analysis

CONTEXT: Adrenal medullary hyperplasia (AMH) is a rare, incompletely described disorder of the adrenal medulla that is associated with catecholamine excess. OBJECTIVE: To increase knowledge about AMH by reviewing the reported cases of this disorder. DESIGN: Systematic review and meta-analysis of the genotype/phenotype relationship in all reported cases of AMH. SETTING: Literature review and analysis. PATIENTS OR OTHER PARTICIPANTS: All cases of AMH published to date. MAIN OUTCOME MEASURE(S): Characteristics of AMH cases and genotype-phenotype relationships. RESULTS: A total of 66 patients, median age of 48 years, were identified from 29 reports. More than one-half were male (n = 39, 59%). The majority had unilateral (73%, n = 48) disease; 71% (n = 47) were sporadic and 23% (n = 15) were associated with the MEN2. Most (91%, n = 60) displayed signs and symptoms of excess catecholamine secretion, particularly hypertension. Elevated catecholamine concentrations (86%, n = 57) and adrenal abnormalities on imaging were common (80%, n = 53). More than one-half (58%, n = 38) had concurrent tumors: pheochromocytoma (42%, n = 16/38); medullary thyroid cancer (24%, n = 9/38); and adrenocortical adenoma (29%, n = 11/38). Most (88%, n = 58) underwent adrenalectomy with 45/58 achieving symptom resolution. Adrenalectomy was less common in patients under 40 years and those with bilateral disease (both P < .05). CONCLUSION: AMH may be sporadic or associated with MEN2, most have catecholamine excess and imaging abnormalities. Unilateral involvement is more common. Most reported patients have been treated with adrenalectomy, which is usually curative with regard to catecholamine hypersecretion.