Thanks to everyone for posting... I reached out to the vet at the Poultry Department at the University of Arkansas. I'm canning this meat so I was concerned about potential parasites or something like that. This is the response from the poultry vet -
Those spots have the appearance of an inflammatory response.
The condition is referred to as IP.
Those yellow-white spots are coagulations of inflammatory cells.
Birds do not form abscesses like we see in mammals . In addition, their skin is loosely attached which allows for movement of inflammation.
The high body temperature also causes the inflammation to coagulate into lumps similar to dried cheese.
Those can be trimmed off and the underlying meat is considered okay but most people prefer to just condemn the meat as unfit for human consumption since it is difficult to determine if all the inflammation has been successfully removed.
The bird most likely has an injury where the IP developed and migrated under the skin.
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It is very possible... The reason I chose to cull roosters last night is because one or more of them was attacking the others. It's a bachelor pen. No hens but I did have 8 week old cockerels in there and one was nearly killed. Tore the back of its head open and ripped off all the feathers entirely from his back. Those chicks have been in there for weeks with no problem. I suspected it was one of the younger roos around 7 or 8 months old causing the ruckus. Anyway, I know the rooster with this granulation was being bullied by some of the others.