Neuroendocrine neoplasms of the orbit: report of three cases and a literature review.

Neuroendocrine neoplasms (NENs) originate from neuroendocrine cells, and mainly occur in the gastrointestinal tract and lungs, rarely occurring in the orbit. Here, the clinicopathologic factors, treatments and prognosis of three cases of orbital NENs are described. The mean age of the three patients (two females and one male) was 59 years. Two cases exhibited ocular symptoms, including unilateral proptosis and eyelid mass, while the third case presented systemic symptoms exhibited as Cushing's syndrome. The tumours were surgically resected in all three patients. Immunohistochemistry assays revealed positive expression for pan cytokeratin and epithelial membrane antigen in all cases. Additionally, neural cell adhesion molecule 1 (also known as CD56) and synaptophysin were positive in two cases. The pathological diagnosis for case 1 and 2 was 'neuroendocrine carcinoma' and both patients died three months after diagnosis. Case 3 was diagnosed with a neuroendocrine tumour and the symptoms of Cushing's syndrome gradually improved following surgery. In addition, no recurrence was observed during the four-year follow-up period. These cases demonstrate that orbital neuroendocrine tumours show different clinical manifestations due to the different types. Pathology may clarify the diagnosis, classification and grading, and provide a reference value for treatment and prognosis.