A survey of pituitary incidentaloma in Japan

The development of computed tomography (CT) and magnetic resonance imaging (MRI) has resulted in the discovery of unsuspected endocrinologically silent pituitary masses (pituitary incidentalomas). The aim of this study was to perform a national survey on pituitary incidentalomas in order to establish an appropriate approach to them.

Five hundred and six patients with pituitary incidentalomas were obtained by questionnaire from March 1999 to May 2000 under the auspices of the Ministry of Health, Labor and Welfare in Japan. Two hundred and fifty-eight patients underwent surgery (surgical group), while 248 patients were followed up conservatively for a mean period of 26.9 Months (range 6-173 Months) (non-surgical group). Clinical and biochemical assessment, CT or MRI of the pituitary, and visual field testing by Goldman perimetry were assessed at baseline and 6 Months and Yearly thereafter.

Thirty-three patients with pituitary incidentalomas (13.3%) developed tumor enlargement during the mean follow-up period of 45.5 Months. Of 115 estimated non-functioning adenomas, 23 tumors (20.0%) increased during a mean follow-up period of 50.7 Months (range 10-173 Months), while 5 of 94 (5.3%) estimated Rathke's cysts increased in size during follow-up. Pituitary apoplexy occurred in one of 248 patients (0.4%).

Pituitary incidentalomas usually follow a benign course. We recommend transsphenoidal adenectomy for a solid mass attached to the optic chiasma estimated to be a pituitary adenoma by MRI. Other patients should be followed up by MRI every 6 Months for the first 2 Years, and then Yearly.