Non functioning pituitary adenomas are the second most commonly occurring pituitary adenoma, a clinical condition which is apparent in 1 in a 1000 patients.
Recent work has suggested that the cut off point of prolactin (pseudo hyperprolactinaemia) with non functioning pituitary tumours is lower than previously thought. In all but very exceptional circumstances if the prolactin is above 2000mU/L a prolactinoma is more likely in the presence of a significant pituitary tumour and this of course affects primary treatment.
We have looked at the rate of progression of micro and macro adenomas over time that are otherwise untreated. Microadenomas may occasionally change in size but virtually never become macroadenomas. Macroadenomas however did change in size and over a period of around 5 years 50% of them increased in size and 50% of these caused new visual field problems. Therefore a patient with a macroadenoma has a significant chance of a tumour size increase and this is important in deciding the optimum timing of treatment.
Pituitary function may improve perioperatively (around 12%). This is in marked distinction to craniopharyngiomas in which no pituitary functional improvement occurs perioperatively.
The assessment of the post operative scan in non functioning adenomas is key to predicting the recurrence later. In patients with an empty sellar this is down to 6% at 10 years. Those with intrasellar residual tumours have around a 30-40% recurrence. However at 5 years those with an extra sellar tumour had a recurrence rate of 80%. Therefore it is likely that post operative residual extra sellar tumour is an indication for radiotherapy in view of the high frequency of continuing growth of the remnant.
Pituitary apoplexy is a rare condition. Previously it has not been clear whether or not these tumours significantly progress with time and our studies here have shown that they can do so but that the rate of progression is significantly less than ordinary non functioning tumours. 35% recurrence at 5 years versus 11%.
In the future much work needs to be done to try and improve the management of non functioning pituitary tumours. Recurrences may be decreased with the use of dopamine agonists and proper prospective studies need to be undertaken in this as in other areas.