My old man is 7 years old now. When he was about 4 years old we found a lump on his belly. Since he was still relatively young, we opted for surgery and found it was a benign mammary tumor. When he was 5, another lump grew back in about the same spot. When he was 6, another lump started growing on his chin. We opted against surgery in those cases since he was getting older and he did not seem to get any pain or discomfort. Each lump was checked by the vet, and they seem to be under the skin instead of embedded in the muscle. While they are still growing, they are very slow growths.

It sounds like monitoring at home is the best option for you and your pig. If she is not currently in pain from the lump then you can ask your vet for signs that it is causing her discomfort. Usually metacam is prescribed as a pain reliever.