54 year old female with a week long history of worsening right lower quadrant, colicky abdominal pain and nausea. Physical exam reveals right lower quadrant tenderness. Laboratory analysis was normal.
CT abdomen and pelvis: Tubular, sausage-shaped lesion in the cecum separate from the ileocecal valve and ileum.
Appendiceal intussusception is a rare entity, with a reported incidence of 0.01% and sparse literature available to characterize it. The literature has historically been in relation to its appearance and its proper management during colonoscopy, isolating it to case reports in gastroenterology and surgery. In fact, the first CT-diagnosed case of appendiceal intussusception was not published until 2006. With the increased accessibility of multi-detector CT and advent of CT colonography, this entity deserves a thorough understanding on the part of the radiologist. The cause of appendiceal intussusception is not entirely understood, though suggested anatomic and physiologic risk factors include persistence of a fetal, wide-based appendix or abnormal peristalsis within the appendix and adjacent cecum. Appendiceal intussusception may present at any age, but is more common in adults. While many patients are asymptomatic, others may present with waxing and waning abdominal pain. Less often, patients may present with vomiting or hematochezia. Physical exam often elicits tenderness, though an abdominal mass may be palpated. It is estimated that over 70% of cases are associated with “lead points” such as endometriosis, mucoceles, and various other benign and malignant neoplasms. It is also estimated that approximately 27% of cases may be solely associated with inflammation without a causative lesion. Careful correlation with history and inspection of the cecum on multi-planar CT imaging or colonography should guide the radiologist to the accurate diagnosis of appendiceal intussusception. An advantage of MDCT and colonography over colonoscopy is that an appendiceal intussusception is unlikely to be confused for a polyp. There are two obscure surgical techniques utilized during appendectomy which may mimic appendiceal intussusception: “dunking,” of the appendiceal stump using a purse-string suture after appendiceal ligation or deliberate inversion of the appendix altogether. Management of symptomatic appendiceal intussusception may include barium or air enema reduction, colonoscopic reduction, and surgical excision. The radiologist should carefully consider the possibility of malignant spread of disease and peritoneal seeding or bowel perforation in those with signs of bowel ischemia before recommending colonoscopic reduction.