It is likely the coin was in a fire and a small air bubble in the metal expanded when heated producing the large lump on the surface.
If that was the case wouldn't the face be rasied as well? The chin is in the normal place,just the metal around it is up.
It is hard to see what you are talking about from your photo. Can you retake it pointing straight in on the coin rather than at an angle?
I agree with Hobo that this quarter was retrieved from a fire and gas trapped between the cupro-nickel jacket and inner copper core expanded causing the bubble. The outline of the device, Washington's face, acted like a thicker buffer area and the gas expanded the area with the least amount of resistance in the field. Happy Collecting
