My dog's benign skin lumps keep reappearing. What should I do?

Thanks for using Petco Pet Education Center, formerly Petcoach and for looking out for Buddy. I'm not sure from your picture if you're talking about the blackish mass at the front of Buddy's chest, or if he has masses under his skin on his sides. Either way the answer is the same.

If the masses are coming back in the same place, then he's either very unlikely or there is local recurrence of the mass. Local recurrence and have been with cancerous growths and also with some more benign types of growths. The appropriate treatment depends on the type of mass that it is. I would recommend asking your veterinarian if he had cytology or histopathology done on the mass for testing (because those would give very different information) and exactly what the growth was. Then you can talk to your veterinarian about the significance of regrowth, or repost a question here if you would like.

Another possibility is that he's getting new masses, in similar but not identical places, and it's unrelated to his old masses. For this I would recommend cytology (using a needle to poke the mass while Buddy is awake) at your veterinary office and talking to them about whether removal is needed or not.