Gallstone ileus presenting as obstructive gangrenous appendicitis.

We present the very unusual case of a 38-year-old woman with acute appendicitis and intestinal obstruction. During surgery, a 2.5 cm gallstone impacted at the base of the cecal appendix was found as the cause of a gangrenous appendicitis and obstruction; a choledochal-duodenal fistula was found during the same surgery with no gallstones remaining in the gallbladder or elsewhere. The case was managed by appendectomy with retrieval of the gallstones and no other procedure was performed for the gallbladder or the fistula, since no other gallstone was found on examination. Previously, she was found to have a round, radio-opaque image on the right iliac fossa on imaging, initially identified as an appendicolith, but after pathological examination it turned out to contain cholesterol and calcium bilirubinate. Gallstone ileus as the cause of an obstructive gangrenous appendicitis is a very unusual disease presentation that should be kept in mind when finding an unusual appendicolith presentation in or out the appendix.