Successful Management of Cushing Syndrome From Ectopic ACTH Secretion in an Adolescent With Osilodrostat

A previously healthy 11-year-old male was found to have a mass in the pancreatic head after several months of abdominal pain and jaundice. Pathology was consistent with a World Health Organization grade 2 pancreatic neuroendocrine tumor. He developed refractory hypertension and was found to have Cushing syndrome from ectopic ACTH secretion, with oligometastatic liver disease. He underwent surgical resection of the pancreatic tumor and metastases. Postoperatively, his Cushing syndrome resolved, but it reemerged 1 year later in the setting of disease recurrence. He was not a candidate for bilateral adrenalectomy. Ketoconazole therapy was inadequate and he was started on metyrapone, lanreotide, cabergoline, and spironolactone. Although this regimen was well-tolerated, his Cushing syndrome recurred 4 months later as his metastatic disease burden increased. Osilodrostat was begun and the dose was gradually increased in response to his uncontrolled Cushing syndrome. Osilodrostat resulted in rapid improvement and eventual normalization of his urinary free cortisol at a dose of 18 mg twice daily. He had no adverse effects. This rare case highlights the successful off-label use of osilodrostat, a medication intended for refractory Cushing disease in adult patients, in a pediatric patient with Cushing syndrome caused by ectopic ACTH secretion.