44 Amyand’s Hernia with Incidental Appendiceal Neuroendocrine Tumour: A Rare Dual Pathology

Abstract Introduction Amyand’s hernia is defined as the presence of the appendix within an inguinal hernia sac. It is uncommon, with an incidence of approximately 1% of all inguinal hernias. Appendiceal neuroendocrine tumours (NETs) are also rare, accounting for 0.5-1% of intestinal neoplasms and found in 0.3-0.9% of appendicectomy specimens. This report describes a case of Amyand’s hernia with incidental NET cells, a combination with only two previous cases reported in English literature. Case Presentation A 29-year-old man was listed for elective TAPP (transabdominal preperitoneal) bilateral inguinal hernia repair. He had no medical/family history. He had a large, long-standing, right-sided inguinoscrotal hernia and a tiny left-sided hernia containing fat. Intraoperatively, a right-sided indirect hernia containing a normal appendix was identified. During the dissection of the appendix from the hernia sac, the tip of the appendix was inadvertently injured with diathermy. Consequently, a decision was made to proceed with a laparoscopic appendicectomy, followed by a standard mesh repair of the hernia. He was discharged the same day after an uneventful recovery. Histopathology revealed a 4.5 mm well-differentiated NET at the appendix tip, invading the muscularis propria without lymphovascular or extramural invasion. The resection margin at the base was clear by >10 mm. The case was discussed at the NET multidisciplinary team meeting. In the absence of high-risk features, no follow-up was required per UKINETS guidelines. Conclusions This case highlights an exceptionally rare coexistence of Amyand’s hernia and appendiceal NET, contributing to limited literature and underscoring the importance of recognising unexpected intraoperative findings.