Hello and happy birthday IHH.
I too have the groves on my toenails and a lovely color pattern very similar to yours by the way, but I noticed you talking about "sharply demarcated edema" then showing a picture of yr fasionably purple foot which is what I personaly like to think of as the rainbow effect (color change lines) not shure what thats called though its not edema.
Edema is the swelling that you get in the RSD area, "demarcated" is an obvious end to the swelling, or defined line where the swelling stops and so called "normal" skin begins (if me memory serves me right).
I get/got what was is called "Brawny Edema" and that is an area of swelling from above my right knee (in a 'rounded sharply demarcated' curve) and down my calf and into my ankle and foot that I could press my fingers into and hold fer a few secs (yes hurts) an it leaves an indented hole
that would show there for hours. I also have edema that is not "brawny" it does not leave an indent.
I learned it is better with all edema to ignore, elevate it, and not poke.. hurts to much an had a bump on my ankle from a pressure point I usta like to press (a spot in my ankle that eleviated some of the pain) but the next few times it swelled bad I got an "out-dent" from it that looked like the bump that Fred Flinstone gets from a bang on his head.