Malignant pituitary adenomas are extremely rare and comprise less than 5% of all pituitary tumors.
A 65-year-old woman had rapid loss of vision and a chiasmal syndrome. Investigation revealed panhypopituitarism, and hyperostosis of the greater wing of the sphenoid bone and x-ray film evidence suggested a tuberculum sella meningioma. When a craniotomy was performed, a pituitary adenoma was found. The patient's death one month later was caused by an abnormal antidiuretic hormone (ADH) syndrome and pulmonary emboli.
Pathological examination revealed an invasive pituitary adenoma, involving the optic nerves and cavernous sinus. The hyperostosis seemed to correlate well with the tumor infiltration. There were, however, no clinical or radiological findings that were diagnostic of malignant pituitary adenomas.
The diagnosis of malignant adenomas should be considered when visual loss is rapid or when there are signs of extension into the cavernous sinus.
Scott TV, Schatz NJ, Lee KF. Malignant Pituitary AdenomaA Cause of Sphenoid Hyperostosis and Monocular Blindness. Arch Ophthalmol. 1974;91(2):123-125. doi:10.1001/archopht.1974.03900060129008