Uncommon sites for metastasis of neuroendocrine tumor in adults
e15683 Background: Neuroendocrine tumours are relatively slow growing tumours. They often present with significant metastatic disease affecting liver, lymph nodes, lungs and bone. However tumour masses may be found at unusual/uncommon sites e.g. breast, orbital soft tissue and the heart raising the possibility of this being metastatic focus or presence of another primary tumour. Detection of these sites could have a significant impact on the available treatment options. Aim: to determine the most appropriate imaging modality and type of tumour metastases. Methods: We reviewed 300 consecutive clinic patients. We identified 18 patients with metastasis at uncommon sites i.e. breast, orbital and cardiac. We retrospectively evaluated clinical notes and recent radiological investigations of these patients. To characterise these lesions additional investigations included cross sectional imaging, PET imaging (68Gallium DOTA Octreotate PET and 18F- FDG PET) and histological evaluation of the metastasis where appropriate. Patients with breast metastasis underwent bilateral mammogram, patients with peri-ocular involvement underwent MRI of the brain and the orbit. Results: 18 patients had tumour masses at uncommon sites. Of these 15 masses were in the breast; 4 were in the orbital muscles and 2 patients had pericardial metastasis. Of the 15 patients with breast lesions 12 had confirmed neuroendocrine tumour metastases and 3 had breast cancer. It should be noted that breast cancer lesions were positive on the 68Gallium Octreotate PET imaging. One patient who had a defined metastasis in the pericardium showed avid uptake on the 68Gallium DOTA Octreotate PET and scan and cardiac MRI, the other patient had pericardial metastases confirmed at post mortem. Conclusions: Clear knowledge of these uncommon sites of metastasis is useful in terms of arranging further investigations and excluding other cancers. It is also important to realise that although somatostatin receptor scintigraphy especially 68Gallium DOTA Octreotate PET is very useful in detecting NET metastasis, it may also show avid uptake in patients with breast cancer and hence histological evaluation of these lesions are important. Undoubtedly within our cohort of patients and generally there is an under-diagnosis of lesions in uncommon sites. No significant financial relationships to disclose.