In a retrospective review of 1640 cases of MTC, at most 0.7% developed ectopic ACTH secretion.2 Of these cases, it has been estimated that the underlying MTC is discovered first in 65% of patients.4 Here, we present a case of a patient diagnosed initially with Cushing’s syndrome who was subsequently found to have metastatic MTC as the source of excess ACTH. The gene discussed is POMC; the disease is medullary thyroid gland carcinoma.