Yes!
Many inflammatory bowels disease patients have been tagged as having UC only to develop complications of Crohn's and some of us have been mis-diagnosed with Crohn's only to find we actually have UC. My diagnosis started as ulcerative proctitis, then ulcerative colitis, then at Cleveland Clinic long ago based on x-ray that showed a skipping pattern, diagnosis changed to Crohn's - and stated that way for decades. But I never developed fistulae or small bowel disease or strictures. Just dysplasia, and most likely Ulcerative Colitis was the correct diagnosis all along.
Unfortunately the course of the disease itself is often what differentiates the diagnosis. I don't think microscopic diagnosis is even definitive.
But there is a test. I had a version of this done to evaluate whether I had adequate levels of 6-MP when I was on that treatment. It also came back that I most likely had UC which turned out to be correct. It's offered by Prometheus Labs. Here's a link that describes how it's done using serologic, genetic, and inflammation markers. It's probably more accurate now then when I had it. https://www.prometheuslabs.com.../ibd-sgi-diagnostic/
I've not thought about this for a while. I wonder if it's being used for pouch patients in some capacity - either before surgery or to evaluate when symptoms develop following.