After having told for 5 yrs "it's just as cyst" I wanted to get a cyto of it and despite the not so clear report, I got told that we were possibly facing MCT and surgery was a must. Of course they denied of ever having seen the cyst (no words). So instead of rushing to a specialist surgeon, I started him on the benadryl/tagamet protocol and the shrinkage we got in two weeks is unbelievable. We will then retest it and see if we get a better answer to decide how to move forward.
With this hype, I decided to put him on raw feeding given all the benefits associated (I've cooked for my dogs for yrs and put them on kibbles for the past year). We feed them 80%meat(gizzards and hearts included) 10%organs 10%bones and veggies purée. They love it!!! Oh I forgot to say, Ugo has always been the healthiest, even after this "report" he is always the same dog. He eats, and a lot, sleeps, plays, calls for treats, runs, stools and pee perfect, no other reason in 7 yrs to go to the vet if not for yearly check ups.
I asked for blood test and X-rays and they turned out great. So independently from this MCT being real or not, raw is my way to go. I don't know as of right now in which of your categories he falls into.