Ablative thyroid treatment for thyrotoxicosis due to thyrotropin-producing pituitary tumours

Background: Thyrotropin (TSH)-secreting pituitary adenomas (TSHomas) are rare tumours that can be invasive. It has been suggested that thyroid surgery or radioiodine treatment should not be considered in patients with such tumours as these treatments may facilitate rapid and aggressive tumour expansion. Aim: To study the effects of thyroid ablative treatment on tumour size and thyroid status in two patients with TSHomas in whom the size of the adenoma was clearly documented before treatment was started. Methods: Patients studied were: (1) a female patient with a TSHoma who declined to undergo pituitary surgery and underwent a total thyroidectomy instead and (2) a male patient who opted for radioiodine treatment for his recurrent TSHoma. Changes in tumour size on serial magnetic resonance imaging scans, and restoration of euthyroidism were studied. Results: No marked changes in tumour size or features of aggressiveness occurred in these patients over periods of 8 and 12 years. Euthyroidism was restored and maintained in both patients. Conclusions: Ablative thyroid treatment can be a safe and successful option to treat TSHomas, but long-term and close follow-up of these patients is mandatory to ensure that the size and behaviour of the tumours do not change markedly.