Has anyone seen this type of tumor? She seems to not be effected by the growth.

[Eggcessive]

I still think it is a dermoid cyst. A vet may be able to tell. They can have all sorts of different kinds of tissue inside them. They are kind of weird looking with tissue from other parts of the body. Someone else posted a picture of one in the last couple of months. I would not attempt to remove it myself.

 

[FlyingNunFarm]

I'm wondering if it's near her oil gland. Trying to figure out location by the picture.

I would say dilated pore of winer as well. If it where a cyst I think it would be enclosed.

 

[Eggcessive]

Dermoid cysts are also called teratomas, and are common in animals or humans. Chickens are also affected by lymphoid tumors from such diseases as avian leukosis and Mareks disease.