While I'm not a vet, it is my understanding that ingrown feathers are caused by a deformed feather or a damaged/deformed follicle & may or may not rupture on its own.
If it does not rupture, the ingrown feather could be absorbed by the bird's body or become further inflamed & require excision by a veterinarian.....actually, I believe if the follicle produces another ingrown, veterinarians will remove the follicle, so that the problem does not continue.....you may want to call & discuss it with your veterinarian, because just as we humans are, birds are subject to tumorous growths that can be fatty, benign or malignant and of virtually any variety.
Avian tumors occur with a greater frequency than we might imagine. As with humans, no particular species or age group can be said to be more susceptible to the occurance of tumors than another, though some may be genetically predisposed to tumor and/or cancer growth, as well as fatty deposits and/or cysts.
Good luck.....
