A patient with Cushing disease lateralizing a pituitary adenoma by inferior petrosal sinus sampling using desmopressin: a case report

A 14-year-old girl was referred for evaluation of the etiology of Cushing syndrome. During the previous 2 years, she had experienced weight gain, secondary amenorrhea, growth retardation, and back pain. Random serum cortisol level, 24-hour urinary free cortisol excretion, and overnight and low-dose dexamethasone suppression tests suggested Cushing syndrome. Midnight adrenocorticotropic hormone (ACTH) level and high-dose dexamethasone suppression test confirmed Cushing disease. Pituitary magnetic resonance imaging was suspicious for microadenoma. To eliminate ectopic ACTH syndrome, and lateralize the pituitary tumor, inferior petrosal sinus sampling (IPSS) was performed by desmopressin use to stimulate ACTH. Finally, the patient was diagnosed with Cushing disease due to ACTH-secreting pituitary microadenoma, lateralized to the left side; subsequently underwent transsphenoidal surgery. Here we report a case of a 14-year-old girl diagnosed with Cushing disease with a pituitary tumor lateralized by IPSS using desmopressin, which is very rare in pediatric Cushing disease.