What Causes Prominent Vein In Chest Radiating To Abdomen?

Have a worm like swelling that is approximately 5 in length running vertical that starts just under my chest and goes down to abdomen area. It doesn t hurt unless I am pressing on it. I have had it going on a week and seems to be getting longer. I am a 35 yr old male and not over weight have no major health issues in family other than heart attacks. Haven t gone to a doc yet as it s not painful unless I mess with it. Suggestions???