Giant pituitary adenomas: clinical characteristics and surgical results.

Although most pituitary neoplasms are benign, some grow rapidly, spreading to extrasellar tissues. Definition of these 'giant' pituitary adenomas (PAs) is not clear. In order to clarify this question, we studied all pituitary macroadenomas operated in our hospital during the last 20 years, differentiating those with diameter > or = 3 cm (n = 43) and attempting to identify their typical features and prognosis. The reason for consultation was local in 58.3% of giant PAs, hormonal in 22.9% and tumour recurrence in 16.7%. Surgery was performed via a trans-sphenoidal approach in 92.5% of cases and succeeded in completely removing the tumour in only 27% of cases. In conclusion, we found that giant PAs are not a special type but the extreme case in the gradient of invasiveness of tumours of adenohypophyseal origin. They are characterized by a higher frequency of neuro-ophthalmological symptoms and hormonal deficits, and poorer response to surgical treatment.