Misleading low-grade appendiceal mucinous neoplasm (LAMN) of the appendiceal orifice: a case report

Introduction: A case of a 74-year-old woman who was planned for endoscopic full-thickness resection (eFTR) of a recently colonoscopy-detected polyp of the appendiceal orifice. Important clinical findings:During the colonoscopy, a polyp prolapsed through the appendix orifice into the cecum.A full-thickness resection device (FTRD) was used to perform a resection, which removed most of the polyp.The histopathology report described dysplastic epithelium extending to the resection margin.The finding corresponded to a sessile serrated lesion (SSL) with low-grade dysplasia. Main intervention and outcome:The medical team advised appendicocecectomy, which was performed using the linear stapler while preserving the ileocecal valve.Twelve days postoperatively, the histopathology analysis was finalized.The neoplasm of the appendiceal orifice was described as a solid, low-grade mucinous appendiceal neoplasm (LAMN) that had invaded the submucosa of the appendiceal wall. Conclusion:The histopathological characteristics of the LAMN cannot be described by analyzing the eFTR-gathered tissue alone.Furthermore, due to the possible risk of dissemination, for appendiceal neoplasms, an appendectomy should be a diagnostic and therapeutic method of choice, coupled with a histopathology analysis.