Endometriosis-induced intussusception of the caecal appendix

Appendicular intussusception is an uncommon entity, with a reported incidence of 0.01%. The diagnosis is difficult and often only performed at the time of surgery. Intussusception has multiple causes including tumours, foreign bodies and polyps. The definitive treatment is surgical, and the extent of resection is determined by the underlying pathology and degree of invagination. Endometriosis is a rare cause of appendicular intussusception, with 194 cases described in the English literature. We report a case of a 42-year-old woman who presented with chronic abdominal pain in the lower right quadrant. A mass at the caecum was identified during investigations for renal stones by CT. Colonoscopy showed a polypoid lesion, with presumed origin in the appendix. Ileocaecal resection was performed because an appendicular tumour was suspected. Pathological examination identified endometriosis of the appendix and associated peritoneum with invagination of the caecum. The patient was discharged 7 days after surgery and is currently asymptomatic.