10 years or so ago I got a chemical burn on the center of my back, right over the spine. Took a good while to heal, and itched badly for 3-4 years.
Then, about 3 years ago I got a lump on the same spot, and the itch returned. Dr cut the lump out and called it some kind of cyst. But the skin was still damaged from the chemical burn years before and took months to heal from cutting out that cyst.
Got a dandy scar there now.
And remembering just now, it wasn't a Dr that cut that out. It was a nurse practitioner.
She got an emergency call while she was working on me that her daughter had just been in a car wreck and had a probable broken neck. The gal stayed calm and sewed my back up proper.
