Morphological and immunohistochemical features of neuroendocrine neoplasms in gastroenteropancreatic tract.

Background And Aims: Neuroendocrine neoplasms (NENs) result from neuroendocrine cell neoplastic proliferation, with both characteristics of endocrine and nerve cells. NENs arise in different localizations but the most common site is the gastrointestinal tract, including the pancreas. The morphology and frequency of NENs in our hospital were evaluated, as well as the correlation between lymph node status and Ki67 proliferative index.

Materials And Methods: Retrospectively, we analyzed NEN pathohistological reports of patients who underwent surgical excision of gastroenteropancreatic tumors in the Clinical Center of Vojvodina in Novi Sad, from 2011 to 2018. The descriptive and correlation statistics were done. Chromogranin A, synaptophysin, CD56, and Ki67 were usually used as immunohistochemical markers.

Results: The study registered 78 surgical specimens. The average age of patients was 58.88 (±17) years, whereby 53.8% were males. The most frequent site was the pancreas (29.5%), followed by the large intestine (26.9%). The mean tumor size was 3.71 (±3.13) cm. No significance was found in tumor differentiation degree (G1 = 32.1%, G2 = 26.9%, and G3 = 29.5%). Lymph node metastases were found in 47.44%. Positive correlation was found between the Ki67 index and the percentage of positive lymph nodes (r = 0.343, p = 0.046, p < 0.05, respectively). The correlation between tumor size and lymph node metastases revealed no significance in our study (r = 0.015, p = 0.480, p > 0.05, respectively).

Conclusion: Most NENs lymph node metastases originated from tumors with a high Ki67 index. The results confirm the use of proliferative index Ki67 as a prognostic marker for the presence of metastases, disease progression, and neuroendocrine tumor prognosis.