Rapid resolution of visual abnormalities with medical therapy alone in patients with large prolactinomas.

Large prolactin-secreting pituitary adenomas with suprasellar extension are often complicated by visual field defects, for which surgical decompression is the accepted treatment. However, surgical management of large prolactinomas is often not curative. This report describes a group of six unselected male patients who presented with visual field defects and reduced visual acuity due to large pituitary tumours with suprasellar extension. All six patients also had loss of libido and/or impotence. A rapid serum prolactin estimation enabled the diagnosis of prolactinoma to be made, and CT revealed a large pituitary adenoma with suprasellar extension. The patients were treated with bromocriptine, in doses increasing from 2.5 to 20 mg daily, as the sole therapy. Symptoms were relieved and serum prolactin levels were restored to normal or near normal; visual field defects resolved and visual acuity recovered in all patients. A repeat CT showed evidence of tumour shrinkage especially of the suprasellar extension, in all the patients. A diagnosis of prolactinoma should always be considered in a patient with a large pituitary tumour. The clinical history and a rapid prolactin assay will confirm the diagnosis. Treatment with bromocriptine leads to rapid improvement in perimetry and visual acuity as well as tumour shrinkage, obviating the need for pituitary surgery.