Cognitive Impairment Caused by Isolated Adrenocorticotropic Hormone Deficiency without Other Hypo-adrenalism Signs - Autoimmune Encephalopathy Mimics

Isolated adrenocorticotropic hormone deficiency (IAD) is a cause of adrenal insufficiency (AI), which shows impaired secretion of adrenocorticotropic hormone (ACTH) with the preserved secretion of other anterior pituitary gland hormones. We herein report a case of IAD complicated by chronic thyroiditis presenting with neuropsychiatric symptoms without other signs indicative of AI that showed complete improvement of the cognitive function after the administration of corticosteroids. The clinical features of our case may be confused with autoimmune encephalopathies (AEs); however, IAD should be strictly differentiated from AEs, as it requires permanent hormone replacement without addition of immunosuppressive agents.