Ectopic Cushing's Syndrome in Pediatric Age

Background: Cushing's syndrome due to ectopic ACTH secretion is a rare clinical condition resulting from a dysregulated ACTH secretion by neuroendocrine tumors. The overall incidence of endogenous Cushing's syndrome is 0.7-2.4 per million people annually, with children accounting for only 10% of new cases each year.

Case report: When the patient first presented clinically, she was a 17-year-old girl who displayed psychiatric symptoms. Blood tests showed diabetes mellitus and hypokalemia. She had hypertension and vertebral collapses. The hormone assay showed hypercortisolism, and because of this, she began taking metyrapone. The results of the 68Ga-PET/DOTATOC and 18FDG-PET scans were negative. The clinical course was intermittent. After one year, a 68Ga-PET/DOTATOC showed a nodule in the thymic lodge. Despite the thymectomy, the hypercortisolism persisted. A subsequent 68Ga-PET/DOTATOC repeated three months after surgery revealed an uptake corresponding to the thymic lodge. She underwent another surgery, which is finally being resolved. ACTH levels were monitored before, during, and post-surgery. The laboratory provided the ACTH results promptly, and thoracic surgeons waited for hormonal results before concluding the procedure. The adopted strategy permitted us to monitor the surgery outcome.

Conclusion: The heterogeneity of ectopic Cushing's syndrome makes diagnosis difficult. 68Ga-PET/DOTATOC proves to be a tracer with good sensitivity and specificity for the identification of ACTH-secreting neuroendocrine lesions. The short half-life of ACTH is found to be a strategy to monitor the complete surgical resection of the neuroendocrine lesion.