Ectopic ACTH production by thymic and appendiceal neuroendocrine tumors - two case reports.

Objective: Ectopic adrenocorticotropic syndrome (EAS) causes approximately 10-18% of cases of Cushing's syndrome (CS) in adults, while in children it occurs much less frequently.

Methods: We report two cases of neuroendocrine tumors (of the thymus and the appendix) in a 12-year-old boy and a 15-year-old girl who presented with the clinical features of CS. Elevated serum cortisol, ACTH, and chromogranin levels were observed in both patients. Diagnoses were made on the basis of a mass in the thymus/appendix region visualized with chest/abdominal CT scan and radiotracer accumulation in scintigraphy in the same areas. Histopathological examinations confirmed the diagnoses of NET.

Conclusions: EAS is an extremely rare endocrine disorder. However, it should be taken into consideration in the diagnostic process of every case of ACTH-dependent CS.