Help identifying a hard lump near my hen's waddle

[laineylane]

Below is one my more allusive hens who is hard to catch, but we saw this lump on her face today. It's very firm to the touch.

Any help with this would be appreciated.

The other side, for comparison:

 

[HappyClucker7]

It's either an abscess or a tumor, although judging by the size of it I would guess it's an abscess. If you can, I would try to cut it open with a sharp knife. If it's an abscess, there should be yellow puss inside that has the consistency of cheese.