I really wouldn't think it would be a tumor in such a young boy, but of course that's a possibility. There was some white thick material that I cleaned out but it was very minimal. I've dealt with a lot of abscesses in various animals and also dealt with multiple feather cysts in canaries. This one has me stumped. I will try some scrambled eggs and if I can get a dewormer into him I will try that too.
Well, he just passed away in my arms. In the interest of science, I cut off the tumor or whatever it was. It was not connected to any of the tissue under the skin. It was definitely NOT an abscess. It was a solid mass with blood supply. So I'm just going to say tumor. I still want to deworm my whole flock just incase.
So sorry for your loss. Was he vaccinated for Mareks disease? If you can save his body, keep it cold in an ice cooler or refrigerate it (don’t freeze,) and send his body to your state vet for a necropsy on Monday morning. Here is a list of state vets to contact: https://www.metzerfarms.com/PoultryLabs.cfm
I just looked back at your photos again. I can't tell where it is anchored on his body exactly, but could it be a hernia of some sort, and it got infected.