Orbital metastases from neuroendocrine neoplasms: clinical implications and outcomes

Purpose Neuroendocrine neoplasms (NENs) may rarely metastasise to the orbit. Published data on epidemiology, incidence and preferred treatment is limited. We present the largest cohort of symptomatic and asymptomatic NEN patients with orbital metastases and data on epidemiological parameters, symptoms as well as diagnostic/treatment modalities used. Methods We identified patients from our internal NEN database of patients who had also undergone Gallium 68 -DOTATATE PET (Ga 68 -DOTA). The diagnosis of orbital metastatic NEN was made on somatostatin receptor imaging and confirmed on a dedicated MRI of orbits. Results We identified 27 patients of 994 patients evaluated with Ga 68 -DOTATATE PET imaging during their surveillance monitoring in our department; 15 female, average age at NEN diagnosis 53 years and orbital metastatic NEN diagnosis 59 years. The majority of NEN primaries originated from small bowel (18/27, 66.4%) or pancreas 4/27 (4/27, 14.8%). Hepatic with or without concomitant skeletal metastases were present in 23/27 (85%) of patients. Ocular symptoms and/or signs were evident in 11/27 (41%) of patients. 5/11 symptomatic patients underwent external beam radiotherapy (EBRT) resulting in complete symptoms resolution. The 5-year survival was estimated at 84.1%. Conclusions Orbital metastases of NEN have a relatively low prevalence, more commonly associated with small bowel primary. Extraocular muscles are primarily affected, irrespectively of liver disease burden. Survival does not seem to be affected. EBRT is an efficacious treatment modality for both symptom relief and tumour growth control. Administration of peptide receptor radionuclide therapy may occasionally induce temporary ocular symptoms, which resolve following treatment with a short course of steroids.