Colonoscopy impressions

Hi and welcome to the forum. Erythematous means red in color and it is characteristic of very mild inflammation or at least irritation. If it was inflammation that they biopsied then it is more likely an infection. What you describe does not sound like cancer as what they'd usually see tissue abnormalities, it just looks weird and biopsies would confirm pre-cancerous changes to your tissue.

It could be Just Irritation: Erythematous is what you see when you get a mild sunburn on your skin, it's the same sort of thing as they saw during your colonoscopy but on the intestinal walls. In fact, I've had Erythematous Mucosa as a result of the colonoscopy prep before, and the biopsies confirmed it was just superficial reddening from my prep (it was on the surface only, not deep enough to be inflammation of any kind). Preps are really harsh on the system and they can redden the walls in places.

It could be from Inflammation: Erythematous can also be from very mild inflammation, when we're inflamed our tissue is engorged with blood and that gives it the red coloration. We can get inflammation within our large intestine due to pathogenic bacteria like Clostridium Difficile and other similar things. It's something that can sometimes clear up on it's own, or required a course of antibiotics. Certainly they must run a series of stool tests to see if any pathogens are found, if they haven't already. It's possible you could have a form of IBD such as Crohn's Disease, Crohn's-Colitis, or Indeterminate-Colitis but they are all very rare conditions within the general population. Do you have any family history with IBD? I'd rule out Ulcerative Colitis entirely due to the location they saw the inflammation (UC always involves the rectum and yours was spared).

It could be from Cancer: Again, very unlikely as what you describe does not sound like cancer. For cancer they'd usually see tissue abnormalities, it just looks weird and biopsies would confirm pre-cancerous changes to your tissue. Not impossible, but I'd put this as the least likely explanation.

All you can do is wait for the biopsy results. Biopsies are king when it comes to diagnosis. I'd also insist on a stool test series to rule out pathogenic causes.

Usually it is more extensive with IBD (although it is possible with Crohn's disease to have more inflammation within the small intestine, which they'd have to do an MRI or other x-ray to find). Do you have any IBD symptoms at all? Blood in stool, abdominal discomfort or pain, diarrhea, urgency, significant weight loss, etc. An infection would be the same symptoms.