A case of fistula of the right common iliac aneurysm to the appendix.

We report a very rare case of spontaneous ilioappendicial fistula with right common iliac aneurysm. After the aneurysm was opened, afferent and efferent vessels were closed following extraanatomical femorofemoral bypass, and the appendectomy was performed. The wall of the aneurysm showed the atherosclerotic change and histologic study of the appendix confirmed the diagnosis of acute appendicitis. Enhanced computed tomography was useful for the diagnosis and the extraanatomical bypass was deemed the most effective operative strategy. The pathogenesis of the fistula was surmised to be related to the appendicitis.