Ocular metastases from neuroendocrine tumors: A literature review

Background Neuroendocrine tumors (NETs) include malignancies with different origins, clinical presentations and prognosis. Synchronous or metachronous ocular metastases from NET are extremely rare. The diagnostic algorithm and the management of this entity has not been established. The aim of our study was to characterize this subgroup. Methods We performed an electronic search in PubMed Library databases for articles about ocular metastases from NET published from 1966 to August 2019. Results We identified 21 manuscripts with a total of 64 cases. The primary origin of the tumor was lung in 28 (43.7%) cases, ileum in 14, unknown in 8, colon in 3, rectum, esophagus, thymus, testicle and liver in 1 case each, and not reported in 6. The histopathological confirmation of NET metastasis was available in 25 cases (39%). The most common sites of intraocular lesions was the uvea in 30 (46.8%) cases, followed by the orbit in 27. Most of the patients (n = 44, 68.7%) presented eye symptoms. Locoregional interventions were performed in 40 patients (62.5%): 15 cases underwent surgery, 19 had external beam radiotherapy, 5 had brachytherapy, and 1 patient received laser photocoagulation. These treatments ensured the local control in 28 of the 40 (70%) cases treated with a locoregional approach. Conclusions Ocular metastases from NETs are exceptionally rare, and originate more frequently from foregut primary tumors (lung, esophageal, and thymic NETs). The most common ocular site of secondary lesions is the uvea, likely due to its high vascularization. Locoregional approaches appear to be effective in terms of local disease control.