Endocrine Abstracts (2018) 55 WH5 | DOI: 10.1530/endoabs.55.WH5

NET or Not? A case illustrating potential difficulties in detecting neuroendocrine tumours

Su Ann Tee1, Robert Andrew James1, George Petrides1, Robert Allcock2 & Petros Perros1,3

1Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle, UK; 2Gateshead Health NHS Foundation Trust, Gateshead, UK; 3Institute of Genetic Medicine, Newcastle University, Newcastle, UK.

A 68-year-old lady presented with a right-sided breast lump detected on routine mammography. Past medical history included type 2 diabetes, asthma, and hypothyroidism following radioactive iodine for toxic multinodular goitre. Staging CT showed 2 presumed metastases in the left lung, and one in the right lung. She was referred for biopsy and/or resection of these lesions. Histology of the left lower lobe lesion showed a typical carcinoid tumour with an adjacent neuroendocrine tumourlet; Ki-67 index<5%. Unfortunately, the left upper lobe lesion was too close to the pulmonary artery to safely excise. She then had an OctreoScan which was negative. Her breast carcinoma was removed and tamoxifen was commenced. An incidental thyroid nodule was also noted and further work-up organised. Her case was discussed in the Neuroendocrine MDT. Histology from her breast resection was reviewed and negative for TTF1 and neuroendocrine markers. Meanwhile, FNA of her thyroid nodule showed Thy1, repeat FNA showed Thy 3f so she proceeded to have a left diagnostic lobectomy. Histology showed a 20 mm papillary thyroid carcinoma with capsular and vascular invasion and extrathyroidal extension, hence completion thyroidectomy was performed. Post-operatively she received 3.7GBq of radioactive iodine. Initial post-ablation scan did not show any extrathyroidal uptake, and stimulated thyroglobulin was 166 ug/l, with negative thyroglobulin antibodies. A year later, thyroglobulin levels started to increase markedly, which raised the suspicion of thyroid cancer recurrence. Repeat radioiodine scan showed no uptake in the neck but showed two areas of uptake in the left lung; USS neck showed no local recurrence; and repeat OctreoScan showed non-specific activity in the left lung. Serial CTs showed a 4 mm increase in the left-sided lesion, with stable appearances of the right-sided nodule. Rediscussion in the MDT concluded that the lung nodules were probable metastases from thyroid cancer all along. The diagnosis was explained to the patient, and due to her lack of symptoms and slow progression of the lesions, further surgery or radioactive iodine was withheld. She remains under close monitoring. This case highlights the potential diagnostic difficulties in diagnosing tumours of neuroendocrine origin, and illustrates various diagnostic modalities and multidisciplinary expertise available. Patients with neuroendocrine tumours may have separate multiple malignancies, and there is a possible association documented in the literature. It is of paramount importance to involve patients in decision-making and consider their symptoms and expectations, as it may be inappropriate to offer treatment when the benefits are uncertain.

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