Thanks for the query
As you have mentioned it seems that your son had duodenal varices
. Actually duodenal varices are very unusual, in upper gastrointestinal tract varices are common in esophagus. Now there are various causes for duodenal or esophageal varices
like Portal hypertension
due to cirrhosis, non cirrhotic portal hypertension, extra hepatic portal vein thrombosis
and so many other. But to reach the diagnosis he must have to go through a battery of investigations. So I would suggest you to visit your doctor again and insist him to investigate for the cause of this condition.
I hope this answers your query effectively.