Gastrointestinal Neuroendocrine Tumours: A Comprehensive Case Series with Histomorphological Correlation at Tertiary Care Hospital, Western India

Background: Gastrointestinal neuroendocrine neoplasms (GI-NENs) are rare and arise from enterochromaffin/Kulchitsky cells and exhibit variable clinical, morphological, and biological behavior. Their diagnosis and grading rely heavily on histopathology and proliferation indices as per the WHO 5th edition classification. Early diagnosis and surgical resection has better outcome.Aim: To describe the histopathological features, grading, immunohistochemical profile, and short-term outcomes of five GI-NENs.Materials and Methods: Five cases of GI-NENs diagnosed over nine months were retrospectively analysed. Clinical details, tumour location, gross findings, histomorphology, mitotic activity, Ki-67 index, and immunohistochemistry (IHC) profiles were analyzed. All details taken from clinical case and laboratory records. Classification and grading were performed using the WHO 2022/5th edition criteria.Results: Patients ranged from 16 to 54 years (mean 39 years) with female predominance. Duodenum was the most common site (three cases), followed by ileum (one case) and appendix (one case). Four tumours were well-differentiated NETs, low grade (three G2, one G1) and one was a poorly differentiated large-cell neuroendocrine carcinoma (NEC). Most NETs demonstrated strong Synaptophysin and Chromogranin A positivity. Ki-67 index ranged from