Characteristics of giant pituitary adenomas.

An analysis of 21 giant pituitary adenomas is presented. Giant pituitary adenomas with a diameter of more than four cm mostly perforate dura and diaphragm, invade the cavernous sinus, and spread extradurally into anterior and middle cranial fossae or into the frontal or temporal lobes. Endocrinologically, a third are prolactinomas, and a half are non-secreting tumours leading to pituitary failure. Clinical, radiological, and operative characteristics lead to the conclusions that multishaped dura-penetrating extension is not due to locally destructive growth, but is the result of late diagnosis. Because radical cure by operation and radiotherapy is hardly likely, early operative treatment is necessary even when an excellent endocrinological response to medical therapy is present.