BACKGROUND
Appendiceal intussusception is rare, identified in approximately 0.01% of appendicectomy specimens, and may be associated with an underlying pathological lead point. This single case describes an appendiceal neuroendocrine tumor (NET) that was radiologically occult despite computed tomography (CT) correctly identifying the appendiceal intussusception. It illustrates how concerning intraoperative findings can influence the extent of resection when preoperative imaging does not identify the underlying cause.
CASE REPORT
A woman in her mid-20s presented with intermittent lower abdominal pain and hematochezia and re-presented 48 hours after discharge with worsening right iliac fossa pain, darker bleeding, nausea, and vomiting. CT demonstrated appendiceal intussusception into the cecum with invaginated mesoappendiceal fat but no definite lead-point mass or lymphadenopathy. At laparoscopy, difficult retraction of the intussuscepted appendix and mesenteric lymph nodes raised concern for occult pathology and contributed to conversion to open right hemicolectomy. Histopathology demonstrated a 19-mm grade 1 NET with focal subserosal extension and metastasis in 2 of 16 regional lymph nodes (pT3 pN1, AJCC version 9 stage III). Ga-68 DOTA-peptide positron emission tomography showed no somatostatin-receptor–expressing residual or metastatic disease.
CONCLUSIONS
A radiologically occult appendiceal NET can present as adult appendiceal intussusception. In this single case, difficult appendiceal retraction and mesenteric lymph nodes influenced the extent of resection when CT showed no lead-point mass or lymphadenopathy. This observation is illustrative and does not establish criteria for right hemicolectomy.

Keywords: Intussusception; Appendiceal Neoplasms; Neuroendocrine Tumors; Colectomy; Decision Making; Computed Tomography; X-Ray