Pituitary gland involvement of the sinonasal tract.

Involvement of the upper aerodigestive tract by a pituitary adenoma is due either to downward extension of an intracranial tumor or to a tumor arising from ectopic (Rathke's pouch) remnants. Sites of predilection for the ectopic adenoma are headed by the sphenoid bone and sinus, followed by the soft tissue of the dorsal pharynx and clivus. Both invasive sellar and ectopic adenomas can be destructive, with the extracranial extension of pituitary adenomas being more locally aggressive. There have been no examples of metastasizing ectopic pituitary tumors.