Three in one: a case report of mixed neuroendocrine tumor, goblet cell adenocarcinoma and low-grade mucinous neoplasm in a single appendix

Appendiceal neoplasms (AN) are an uncommon condition that are typically diagnosed incidentally following an appendicectomy for appendicitis. However, there has been an increased incidence of AN, thought to be secondary to the increased use of computer tomography scans. Therefore, understanding of a broad range of differentials and management of potential AN is necessary for general surgeons. This case report describes an exceptionally rare occurrence of three distinct neoplastic processes—mixed neuroendocrine tumor, goblet cell adenocarcinoma, and low-grade appendiceal mucinous neoplasm—coexisting within a single appendix. We believe this case provides valuable clinical and pathological insights into the broad range of AN, highlighting the diagnostic challenges and the role of the multidisciplinary team.