Abstract: Objective · To investigate the clinicopathological features, diagnosis and prognosis of rectal neuroendocrine neoplasms (R-NENs). Methods · The clinical data of 113 cases of R-NENs, January 2008 to June 2017, were collected in Renji Hospital, Shanghai Jiao Tong University School of Medicine, and the clinicopathological features and prognostic factors were retrospectively analyzed. The of synapsin (Syn), neural cell adhesion molecule (CD56), and chromogranin A (CgA) were observedimmunohistochemistry in the R-NENs specimens. The specimens were also observed after hematoxylin-eosin staining. Results · In 113 cases of R-NENs, there were 59 males and 54 females, and their ages ranged 25 to 83 with an average age of (52.3±13.3) years old. All the patients had no obvious clinical manifestations. The main symptoms included changes in bowel habits (21.3%), abdominal pain (8.9%) and anal symptoms (6.2 %), and 63.7% of cases were found in routine medical examinations. The R-NENs were diagnosed as G1 (79.6%), G2 (11.5%), and G3 (8.8%). Immunohistochemistry results demonstrated that 94.7% of tumors were positive for Syn, 80.9% for CD56, and 48.6% for CgA. Till November 2017, the median survival time was 33.10 months (0.40–114.67 months), with 1-year, 3-year, and 5-year survival rates of 93.8%, 90.0%, and 85.9%, respectively. The pathological grade, depth of tumor invasion, lymph node metastasis or distant metastasis, tumor size, and age were all associated with prognosis of patients with R-NENs. Conclusion · Most of R-NENs are low-grade malignant tumors with good overall prognosis and have a lack of specificity in clinical manifestations.

Key words: neuroendocrine neoplasms, rectum, pathological feature, prognosis