Complete appendicular inversion: the "inside-out" appendix. An unusual presentation of Crohn's disease. A case report and review of the literature.

Intussusception of the appendix into the caecum is an uncommon condition and the diagnosis is rarely made preoperatively. Specific anatomic requirements as well as pathological conditions that cause irritation or increased peristalsis should be present for this event to occur. A case is discussed in which the diagnosis was made preoperatively by barium enema and in which the lead point was a large inflammatory polyp due to Crohn's disease. It appeared in this case that inflation at the time of the barium enema resulted in reduction of the intussusception.