[Positron emission tomography (PET) of an invasive ACTH-producing pituitary adenoma].

We report a case of large, invasive ACTH-producing pituitary adenoma with PET study. In CT scans, an intra- and supra-sellar mass diminished after replacement therapy for primary hypoadrenalism. Two years and seven months later, the tumor grew and extended into the neighboring structures. 11C-methionine accumulated markedly in the tumor, and depicted the lateral and dorsal extension.