Large somatostatin-insensitive thyrotrophin-secreting pituitary tumour responsive to D-thyroxine and dopamine agonists.

A unique thyrotrophin (TSH)-secreting pituitary tumour is described in a patient with a history of recurrent thyrotoxicosis. Unlike other previously reported TSHomas, the tumour is insensitive to octreotide, a somatostatin analogue. It does not accumulate [111In]octreotide but expresses functional dopamine receptors and responds to the D-isomer of thyroxine, two characteristics beneficial in the management of the patient.