Silent and Unusual Pituitary Adenomas

Silent pituitary adenomas are tumors responsible of hormone synthesis but without any sign of hypersecretion. If partially silent, they are called “whispering “adenomas. Silent PitNETs are usually discovered when they are large or incidentally. Silent corticotroph pituitary adenomas are considered to be more aggressive than non-secreting adenomas. They frequently invade the cavernous sinus, may have a more rapid growth, can present with pituitary apoplexy, and can recur. Rarely, a silent corticotroph PitNET may transform into an active adenoma responsible for Cushing’s disease. The diagnosis of these silent PitNETs can be considered in the presence of a particular microcystic pattern seen on T2WIs particularly if the cysts diameter is less than 3 mm and if these cysts cover at least 25% of the solid part of the tumor. Thyrotropin-secreting pituitary adenomas represent a very rare cause of hyperthyroidism. These tumors may present a fibrous compartment and/or calcifications. Medical treatment with somatostatin analogs is another option if surgery is not selected.