Pituitary incidentaloma: to operate or not to operate?

The wide use of sophisticated imaging techniques has led to the discovery of asymptomatic pituitary lesions, which are called 'incidentalomas'. Their global prevalence averages 10% whereas that of macroadenomas (> 10 mm) is less than 1%. The most frequently encountered lesions are non-functioning adenomas followed by Rathke's cleft cysts. Physiological pituitary hypertrophy is also frequent in young women. Silent functioning adenomas especially prolactinomas can be found among incidentalomas. Hypopituitarism appears to be more frequent in larger lesions but can occur in microadenomas (< 10 mm). The incidence of tumour growth is higher in macroadenomas and solid lesions in comparison with microadenomas and cystic lesions. The baseline evaluation should include in all patients a complete history and physical examination, a screening for hormone hypersecretion and hypopituitarism and a visual field examination if the lesion abuts the optic nerves or chiasm. If there is hormone hypersecretion, an appropriate treatment is indicated (dopamine agonists for prolactinomas and surgery for tumours producing GH, ACTH or TSH). If there is hypopituitarism, adequate hormone replacement therapy is required. According to recent guidelines, the indications for surgery of non-functioning incidentalomas include a visual field deficit, other visual abnormalities such as ophtalmoplegia or a lesion abutting the optic nerves or chiasm on magnetic resonance imaging (MRI). Regarding the follow-up of incidentalomas not meeting the criteria for surgery, the following tests should be performed: MRI at 1 year for micro-incidentalomas, at 6 months for macro-incidentalomas and then less frequently if unchanged in size, visual field examination for lesions enlarging to abut or compress the optic nerves or chiasm (6 months and yearly) and endocrine testing for macro-incidentalomas (6 months and yearly). Nowadays, data are insufficient to suggest the routine use of medical therapy in non-functioning tumours. Pituitary radiotherapy may be useful as an adjunctive treatment for tumour remnants growing progressively.