Natural history of true pancreaticoduodenal artery aneurysms.

Advances in non-invasive diagnostic techniques, such as CT and ultrasonography, have improved our ability to detect unruptured pancreaticoduodenal artery aneurysms. No definitive study evaluating the natural history of these lesions or their preferred method of treatment has been published. In this report, we describe five patients with eight unruptured true pancreaticoduodenal artery aneurysms followed without treatment. Of these patients, four had coeliac axis stenosis (n = 1) or occlusion (n = 3) and one had occlusion of the superior mesenteric artery. The mean diameter of the aneurysms was 12.0 mm (range 7-17 mm). The mean duration of follow-up was 29.4 months (range 6-57 months). There was no aneurysm rupture during a total of 147 patient-months (243 aneurysm-months) of follow-up. Of the eight aneurysms, three increased in size over the follow-up period. We conclude that the risk of rupture of true pancreaticoduodenal artery aneurysms might be lower than expected from the data on ruptured aneurysms; however, careful follow-up of untreated aneurysms is necessary.