Clinicopathological Profile and Outcomes of Appendiceal Neuroendocrine Tumors: A 10-Year Single-Center Study of 5,483 Appendectomy Specimens

BACKGROUND/AIMS: This study aims to assess the demographic, histopathological, and immunohistochemical (IHC) features of appendiceal neuroendocrine tumors (aNETs) and investigate their associations with tumor location, grade, size, and pathological stage.The follow-up data on survival and surgical outcomes is utilized to improve risk stratification and management strategies. MATERIALS AND METHODS:A retrospective analysis was conducted on 5,483 appendectomy specimens evaluated between 2010 and 2020 in a single tertiary center.Among 115 neoplastic lesions, 45 cases were confirmed as aNETs.Demographic data, histopathological parameters, and IHC markers were reviewed.Survival data were collected from national records. RESULTS:The median patient age was 35, with a female-to-male ratio of 1.37.Most tumors were located in the distal appendix (70.5%) and graded as G1 (82.2%).Mean tumor diameter was 0.91 cm, and the median Ki-67 proliferation index was 1%.Tumor grade and size were significantly associated with both tumor location and pathological tumor stage.Diffuse and proximal tumors were more likely to be G2, larger in size, and in advanced stages (pT4).Lymphovascular invasion, perineural invasion, and surgical margin positivity were more frequent in higher pT stages.Chromogranin A negativity was observed exclusively in pT1 cases.CONCLUSION: aNETs are typically small, well-differentiated tumors with indolent behavior.However, tumor location, size, grade, and invasion features are associated with pathological stage and may serve as prognostic indicators.These parameters should be considered collectively to optimize clinical decision-making and surgical planning.