Hufeisenform der Appendix vermiformis
A horseshoe appendix is an extremely rare variant of the vermiform appendix, in which the appendix arises from the cecum and curves back on itself to re-insert into the cecum, similar to a semicircular canal in the inner ear.
Epidemiology
Anatomic variation of the appendix is extremely rare. In a study of 50,000 appendix surgical specimens by Donald C Collins, an American general surgeon and pathologist, appendiceal agenesis was only seen in four cases, and duplication was seen in two cases, a prevalence of 0.004%. But no cases of horseshoe appendix were seen . In total eleven cases of horseshoe appendix have been reported in the English medical literature with a further four in the Chinese literature .
Gross anatomy
The appendix forms a loop with two appendiceal orifices and in theory at least acute appendicitis should be less likely as it is no longer a blind-ending tube, although at least one case has been described .
History and etymology
The first case was described as recently as 1989 by Thomas W Mesko, an American surgeon, and colleagues .