A young male having a history of TSA for presumed nonfunctioning pituitary adenoma developed clinical and biochemical features of Cushing syndrome starting a year after the surgery. The etiology of Cushing was uncertain; it was initially suspected to be drug-induced but later excluded based on the history and elevated plasma ACTH and cortisol levels. Ectopic Cushing syndrome could not be confidently ruled out, and repeat pituitary surgery was undertaken because of the recurrence of NFA with optic chiasmal compression. Finally, the positive immunostaining for ACTH in the resected tumor established the diagnosis of CD where a coticotroph adenoma that was previously silent had become functionally active producing the stigmata of Cushing syndrome.