The following 3 videos are only a minute or so each and give a pretty good overview of the size, shape and consistency of the lump over the last 4 months.
The lump used to be one solid mass, and then in 2016 it seemed like it was a second mass was growing right next to the first one increasing the overall size of the lump.
Below is a collection of all the pictures I could find showing the size of the lump over the years…
The lump has never seemed to bother him. He is not sensitive to it being touched, and a vet once told me he thought it was most likely a lipoma. I wonder though if it could be that his body encased the microchip he was given when the microchip broke, as the microchip no longer scans, and maybe it was also aggravated by the GPS on his collar. But below you can see Dillinger still is active and healthy at 11 years old.