Incidental finding of synchronous neuroendocrine tumor of appendix and rectal adenocarcinoma. A case report and literature review

Abstract

Abstract Objectives Colorectal cancers represent the predominant malignancies affecting the gastrointestinal tract. In contrast, appendiceal tumors occur less frequently. Among them, appendiceal neuroendocrine tumors (ANETs) account for approximately 50 % of cases and are often detected incidentally during unrelated procedures. Case presentation We present an extremely rare case of an incidental neuroendocrine tumor of the appendix discovered during surgery for rectal adenocarcinoma and provide a review of the relevant literature. A 70-year-old patient with radiologically and endoscopically diagnosed rectal cancer underwent a low anterior resection with total mesorectal excision and a temporary diverting ileostomy following preoperative chemotherapy and radiation therapy. Intraoperatively, a small appendiceal mass was discovered and excised. Histopathological examination confirmed a well-differentiated NET of the appendix measuring 0.4 cm in diameter. Conclusions This case report emphasizes the importance of thorough intraoperative examination during colorectal surgeries and highlights the need for increased awareness of appendiceal NETs among surgeons.