A010

A case of metastatic neuroendocrine tumour with co-existing TSH-secreting pituitary tumour

D Hirani, S Khan, S Jarvis, M Moriarty, T Ladha, Z Halil, A Mahmood, V Bravis, F Wernig. Affiliations: St Mary’s Hospital Endocrinology Department, Imperial Healthcare NHS Trust, London

Abstract: Neuroendocrine tumours (NET) account for <1% of all malignancies, with common primary sites being the gastrointestinal tract and the lung. Presentation with metastatic disease is not uncommon but well-differentiated tumours are associated with a good prognosis (1).

We present the case of a 61-year-old man, who was referred with abnormal thyroid function tests (TSH 1.51miu/L, free T4 23.3pmol/L, T3 7.2pmol/L). On history taking, he reported a 1.5-year history of persistent diarrhoea, facial flushing and self-resolving palpitations associated with alcohol consumption only. He had had a normal colonoscopy. He denied any weight loss and was clinically euthyroid.

Tests showed raised serum chromogranin A (104pmol/L), urinary 5-HIAA (144.3µmol/day), raised Free T3 (7.9pmol/L) and inappropriately non-suppressed TSH (1.80 miu/L). MRI pituitary showed 1.6cm pituitary macroadenoma. TRH stimulation results are shown in Table 1 below, with an alpha subunit pituitary polypeptide level of 0.14UI/L. DOTATATE PET CT showed metastatic neuroendocrine disease involving septal myocardium, peritoneum, liver and bone, with likely primary in small bowel. Liver biopsy confirmed presence of NET with a Ki-67 index of 1% (Grade 1). He was started on Lanreotide and Denosumab injections with good effect. He has also been referred for neurosurgical review towards likely surgery and is awaiting cardiology and genetics follow up.

Time

Serum free T4 (pmol/L)

Serum TSH level (miu/L)

0min

16.4

0.10

30min

16.9

0.10

60min

17.1

0.10

Table 1: Thyroid-releasing hormone stimulation test results

Conclusion: This patient presented following incongruent thyroid function tests that were subtle and certainly raised the differentials of thyroid hormone resistance and TSH secreting tumour. His carcinoid was diagnosed following the history he provided, which was unusual. He indeed had an unusual combination of metastatic neuroendocrine disease, and TSH secreting pituitary macroadenoma. Further genetic testing will help determine if these two findings are connected. This case highlights the importance of accurate history taking, repeating endocrine tests appropriately and the accurate interpretation of them in rational sequence, as well as the need for multi-disciplinary input in the diagnostic and management process.

1.     Oronsky B, Ma PC, Morgensztern D, Carter CA. Nothing But NET: A Review of Neuroendocrine Tumors and Carcinomas. Neoplasia. 2017;19(12):991-1002. doi:10.1016/j.neo.2017.09.002.