Endocrine Abstracts

Introduction: Neuroendocrine tumours can metastasize to the bones, but rarely to the orbit. The majority of orbital metastasis are incidental findings on somatostatin receptor imaging. Symptomatic metastases are treated with external beam radiotherapy or chemotherapy, seldom with surgical resection (1–4). Here we present a case who presented with visual disturbance due to an orbit metastasis which was resected and the histology showed a metastatic NET.

Case: A 56-year male patient, with no past medical history, presented in early 2023 with visual disturbance of his left eye, optician and ophthalmology review noticed ptosis. A MRI head demonstrated a well circumscribed lesion on left rectus muscle. Due to the unclear nature of the lesion a left lateral orbitotomy was performed. The histology showed a well differentiated NET with Ki-67: 3.8% and mitotic count 5 per 2mm². After receiving the histology report a CT chest, abdomen and pelvis and subsequently a ⁶⁸Gallium-DOTATATE PET scan were performed which showed an ileocaecal primary with local lymph node metastases, peritoneal-, bilobar liver- and multiple bone metastases, which all showed avidity on the PET scan. The patient was referred to a NET expert centre. He recovered well from his left lateral orbitotomy. He denied any abdominal symptoms or symptoms of carcinoid syndrome. His performance status was 0. His urine 5-HIAA was 6 times upper limit of normal. He was commenced on monthly somatostatin analogue injections which he tolerated well. Unfortunately 6 months later his ⁶⁸Gallium-DOTATATE PET scan showed new avid peritoneal lesions. He was still asymptomatic and was referred for peptide receptor radionuclide therapy (PRRT). He recently had his first cycle.

Conclusion: Patients with an unclear nature of an orbit lesion could benefit from multi-disciplinary approach as a neuroendocrine tumour metastasis is in the differential diagnosis. Especially, when metastases are considered patients could benefit from early cross sectional imaging and referral to a cancer centre.