I had a Cruel Incision of around 20 damage on my character, from getting mauled by a bear, along with some other long term injuries such as multiple Severe Maulings and Something Broken, however I noticed today I no longer have it and I can't remember how I possibly could've treated it. I looked up the treatments (Gauze, Stitch Patch, Rootfill) and none of those are things I've ever crafted. I have gotten an Ancient Root exactly once and I gave it to my neighbor. I do, however, usually leave leeches on me to deal with various other wounds but I don't think it's likely they'd treat Cruel Incisions.
I can't really complain, cause it's only convenient, but I would like to know why or if it might be some kind of bug.