Endocrine Abstracts

We report a new diagnosis of a pituitary TSH-oma together with a metastaticneuroendocrine tumour. A 61 year old man presented with a 3-year history of diarrhoea. His past medical history includes paroxysmal atrial fibrillation, for which he has had an ablation in the past. He takes no regular medications. Initial investigations were suggestive of hyperthyroidism in the context of unusual thyroid function test results (elevated freeT4 and freeT3 with elevated TSH). A pituitary MRI revealed a pituitary macroadenoma, measuring 1.5 cm in size. Whilst being investigated for a possible TSH-oma, due to the presence of flushing alongside his diarrhoea, two 24 urinary 5-HIAA samples were sent, both of which returned elevated. Chromogranin A was also elevated, and he underwent a Gallium DOTATATE PET CT scan which was suggestive of a metastatic neuroendocrine tumour with metastatic spread to the liver, the bones, the peritoneum as well as focal indeterminate cardiac septal activity. A liver biopsy confirmed a grade-1 neuroendocrine tumour with a Ki-67 labelling index of 1%. Cardiac MRI confirmed myocardial neuroendocrine tumour involvement. The patient was commenced on somatostatin analogues which normalised his thyroid function tests. In view of his bone metastases, he was also started on denosumab. In view of him having two rare conditions, he has been referred for genetic testing although he has no family history of similar conditions. To our knowledge, this is the first reported case of a coexisting TSH-oma and a metastatic neuroendocrine tumour. Whether there is a genetic link between those two rare pathologies or whether they occurred coincidently remains to be seen.