Aneurysms of anomalous splenomesenteric trunk: clinical features and surgical management in two cases.

Aneurysms of the splenic artery that anomalously arise from a splenomesenteric trunk are a rarity. Aneurysmal disease of visceral arteries is found in only 0.2% of the general population. The celiac trunk and superior mesenteric artery (SMA) are involved in less than 10% of all visceral aneurysms. Although rupture seems to occur in 20% to 22% of patients, the related mortality rate can rise as high as 100%. Anomalies of the celiac trunk and SMA, more common than previously claimed, include the splenic artery arising from the SMA, which occurs in only 1% of patients. We present two cases of young patients who had 4-cm aneurysms behind the pancreas that involved an anomalous splenic artery. The first patient required dissection of the entire splenopancreatic bloc through a transverse abdominal incision to excise the aneurysm and repair the SMA. The second patient was treated by the classic approach, through a median incision and by entering the mesenteric root. There do not seem to be reports of similar cases, except for two cases of aneurysms involving the celiomesenteric trunk. The cause of these aneurysms can be attributed to mesenchymal alterations during the embryonic formation of aortic collateral branches. A correct surgical approach to splanchnic aneurysms calls for awareness of potential vascular variations of the arteries and their collateral pathways.