Laparoscopic Right Hemicolectomy of a Low-Grade Appendiceal Mucinous Neoplasm Causing an Ileocolic Intussusception: A Case Report

Intussusception, although common in the pediatric population, rarely occurs in adults. Furthermore, patients often show nonspecific symptoms. Most adult patients with intussusception have a surgical lead point, a well-defined pathological abnormality, often accurately diagnosed after surgery. A low-grade appendiceal mucinous neoplasm (LAMN), often misdiagnosed as acute appendicitis, is rarely associated with the development of intussusception. Here we report a case of LAMN-related ileocolic intussusception that was histologically diagnosed after laparoscopic right hemicolectomy. A 58-year-old woman visited our emergency department because of intermittent episodes of epigastric pain with periumbilical tenderness. These symptoms persisted intermittently for 2 weeks. The pain was moderate in severity, colicky in nature, and sometimes shifted to the lower abdominal region. Abdominal computed tomography indicated intussusception with ileocecal and mesenteric telescoping into the transverse colon. Complete colonoscopy with reduction of intussusception was performed, revealing a ball-like mass protruding and occupying the entire cecum lumen. Laparoscopic right hemicolectomy was then performed. Macroscopically, a dilated appendix was revealed with mucin content, along with hyalinization and fibrosis of the appendiceal wall. Microscopically, a tumor exhibiting villous and flat proliferation of mucinous epithelial cells with low-grade nuclear atypia was seen. However, there was no infiltration growth of the tumor cells, thereby demonstrating LAMN. Postoperative recovery was uneventful, and the patient was discharged on the 8th postoperative day without surgical complications. The differential diagnoses of chronic and colicky abdominal pain should be expanded to include intussusceptions as they can be severe, although cases in adults are rare.