Appendiceal intussusception: what is the appropriate extent of resection?

Appendiceal intussusception is a rare entity with an incidence of 0.01% of appendicectomy specimens.1 It was first reported in 1858.2 It is recommended that an approach of limited resection be employed. An asymptomatic 69-year-old female was referred for consideration of colonoscopy after a positive faecal occult blood test. She had a family history of colon cancer and regularly participated in screening. Physical examination was unremarkable. Colonoscopy demonstrated a protruding lesion at the appendiceal orifice (Fig. 1). Biopsies confirmed normal mucosa. A CT was reportedly unremarkable, though mild appendiceal thickening without a clear mass lesion can be appreciated (Fig. 1). Intra-operatively, an appendiceal intussusception was identified (Fig. 2). The normal-appearing caecum was mobilized to ensure adequate clearance of the ileocaecal valve to facilitate a limited stapled caecectomy (Fig. 3). Histology confirmed a 6 mm grade-one neuroendocrine tumour involving the distal appendix, for which treatment was considered complete. The patient recovered without complication and was discharged the next day. Appendiceal intussusception in adults is rare with few reports in the literature.3-6 Appendiceal intussusception on imaging may be suggested by a 'coiled-spring' appearance,7 but can be difficult to diagnose pre-operatively.4 In this case, the endoscopic appearance was more suggestive than the CT findings. Awareness of appendiceal intussusception is important to prevent attempts at endoscopic polypectomy, which could result in incomplete resection.4 The underlying aetiology in intussusception is more commonly secondary to a benign process such as endometriosis or inflammation4, 5 than malignancy.5 However a neoplastic focus is identified in approximately 2% of resected specimens.8 With respect to surgical decision-making, a partial caecectomy, preserving the ileocaecal valve and limiting mobilization, is often adequate. An upfront right hemicolectomy or ileocolic resection would often represent over-treatment for benign disease and expose the patient to additional risk. Further, should malignancy be diagnosed following partial caecectomy, this procedure does not hinder the ability to proceed with formal resection thereafter if required. A classification system reflecting the degree of invagination has been described in children to guide surgical options.9 However, unless a gross abnormality of the appendiceal base is noted, or the ileocaecal junction would be compromised, a partial caecectomy is an appropriate first approach in modern management. Appendicectomy is similarly recommended as treatment in paediatric populations.10 Ultimately, limited resection in appendiceal intussusception to facilitate pathological assessment prior to formal resection is prudent. A high index of suspicion is required for underlying pathology, and although benign pathologies are more common, endoscopic resection is not recommended. Open access publishing facilitated by University of New South Wales, as part of the Wiley - University of New South Wales agreement via the Council of Australian University Librarians. Ashley Jenkin: Conceptualization; data curation; writing – original draft; writing – review and editing. Edward A. Cooper: Conceptualization; data curation; supervision; writing – review and editing. David Z Lubowski: Conceptualization; supervision; writing – review and editing.