Impaired 11β-HSD1 Activity in a Male Patient With Cushing Disease Resulting in Lack of the Full Cushingoid Phenotype.

We present a patient who had surgically confirmed CD but without the full cushingoid phenotype despite markedly elevated cortisol. Nonpathologic causes of elevated ACTH and cortisol were eliminated as were pathogenic variants in the glucocorticoid receptor gene. Further studies of urine metabolites, cortisol half-life, and the ratios of cortisone to cortisol conversion revealed impaired 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) activity. There have only been 2 prior reports of impaired 11β-HSD1 resulting in lack of classic cushingoid features in the past 2 decades. Our patient's presentation and previous reports demonstrate the key role of 11β-HSD1 in modulating intracellular cortisol concentration, therefore shielding the peripheral tissues from the effects of excess cortisol. When patients present with markedly elevated cortisol but without classic cushingoid features, impaired 11β-HSD1 should be considered in the differential diagnosis.