When anorexia nervosa conceals Cushing syndrome: a diagnostic pitfall in hypercortisolemia

A 37-year-old woman presented with severe hypertension, mood changes, and weight loss (body mass index 14.6 kg/m²). She exhibited restrictive eating behaviors consistent with anorexia nervosa, alongside biochemical hypercortisolemia with serum cortisol 43.6 µg/dL (1204 nmol/L; reference range: 6.2-18.1 µg/dL; 170-500 nmol/L), 24-hour urinary free cortisol 430.3 µg/24 hours (1187 nmol/24 hours; reference range: <60.2 µg/24 hours; <166 nmol/24 hours), and unsuppressed adrenocorticotropic hormone of 19.1 pg/mL (4.2 pmol/L; reference range: 7.3-63.1 pg/mL; 1.6-13.9 pmol/L). The cortisol level after the 1 mg dexamethasone suppression test was 23.9 µg/dL (659 nmol/L; reference range: <1.8 µg/dL; <50 nmol/L). Cortisol remained markedly elevated after nasogastric feeding and weight restoration. Pituitary magnetic resonance imaging revealed a 4 mm left anterior pituitary lesion. High-dose dexamethasone suppression, corticotropin-releasing hormone stimulation, and inferior petrosal sinus sampling confirmed a pituitary source of adrenocorticotropic hormone. The patient underwent transsphenoidal resection of a corticotroph adenoma. Eleven months later, her hypertension and restrictive eating behaviors had resolved, and her mood significantly improved. Cushing syndrome can coexist with anorexia nervosa, masking typical cushingoid features and presenting with psychiatric manifestations and weight loss. Persistent hypercortisolemia despite nutritional rehabilitation should prompt dynamic endocrine testing and pituitary evaluation to ensure timely diagnosis and treatment.