Biopsy/Pathology Terms in UC: “Chronic Active Colitis,” Crypt Abscesses, Dysplasia
Last Updated Jan 15, 2026
A biopsy (small tissue sample) taken during colonoscopy can add helpful detail to an ulcerative colitis (UC) picture. The colonoscopy shows what the lining looks like to the eye, while the biopsy shows what is happening under the microscope. Because of that, pathology wording can sound intense even when symptoms feel calm, or when the colon looks mostly healed.
How biopsies fit with colonoscopy scoring
During colonoscopy, gastroenterologists often describe inflammation severity based on visible changes in the colon lining, such as redness, bleeding, or ulcers. In research studies, a common way to summarize this is the Mayo Endoscopic Subscore, which grades what is seen during the exam. Biopsies add a second layer: they can detect “microscopic inflammation,” meaning immune cells and subtle injury that may not be obvious by sight alone.
This difference helps explain why a report can mention ongoing inflammation even when the colonoscopy looks improved. Pathologists separate findings into signs of activity (inflammation happening now or recently) and signs of chronicity (changes that build up after inflammation has been present over time). In classic UC, this often shows up as “chronic active colitis,” meaning both types of findings are present: active inflammation plus tissue changes linked to longer-term injury. [1]
“Chronic active colitis,” crypt abscesses, and basal plasmacytosis
People often search for the chronic active colitis meaning because it sounds like a new diagnosis. In plain English, it usually means: the biopsy shows evidence of long-standing UC-type inflammation (chronic) and evidence of inflammation that is currently “turned on” (active).
Common terms that may appear alongside it include:
- Crypt abscess: a cluster of neutrophils (a type of white blood cell) collecting inside the colon’s glands (crypts). This is a sign of active inflammation. [2]
- Basal plasmacytosis: extra plasma cells gathered near the base of the lining. This pattern is considered an early and fairly predictive feature of inflammatory bowel disease (IBD), including UC, and it can support that inflammation is real even if other findings are subtle. [3]
- Cryptitis (often listed near crypt abscesses): neutrophils moving into the crypt lining, also a sign of active inflammation (often grouped with “activity” in UC reports).
These are descriptions of patterns a pathologist sees. They do not, by themselves, measure day-to-day symptoms, and they can overlap with other causes of colitis, which is why biopsy results are typically interpreted together with colonoscopy findings and the broader clinical story.
Dysplasia in UC and what it means for colon cancer surveillance
Dysplasia in UC refers to precancerous cell changes in the colon lining. In UC, most colorectal cancers are thought to arise from dysplasia over time, which is why many care plans include regular colonoscopy surveillance for people with UC that extends beyond the rectum. [4]
Pathology reports may describe dysplasia as:
- Negative for dysplasia: no precancerous changes seen in the sampled tissue.
- Indefinite for dysplasia: changes are suspicious, but inflammation or healing makes it hard to be sure.
- Low-grade vs. high-grade dysplasia: a way of describing how abnormal the cells look.
Because dysplasia is closely tied to surveillance decisions, expert groups recommend structured follow-up over time. For example, the American College of Gastroenterology notes that screening and surveillance colonoscopy for dysplasia in UC affecting more than the rectum generally starts about 8 years after diagnosis, with repeat exams typically every 1 to 3 years depending on risk factors and prior findings. [4] The Crohn’s & Colitis Foundation also highlights that longer disease duration and colonic involvement raise colorectal cancer risk, and surveillance intervals are commonly in the 1 to 3 year range based on individual risk. [5]