Aberrant p53 in benign colonic biopsies foreshadowed dysplasia in PSC-colitis

Design

Retrospective case-control immunohistochemistry study

Population

25 PSC-IBD patients who later developed dysplasia vs 20 IBD controls without neoplasia

Primary outcome

Aberrant p53 overexpression in prior benign biopsies

Effect

36% vs 5% of patients; sensitivity 36%, specificity 95% for subsequent dysplasia

Colitis associated with primary sclerosing cholangitis carries a higher risk of colorectal dysplasia than colitis alone, often flat, invisible and right-sided. A US group stained 91 histologically benign biopsies from 25 patients with PSC and inflammatory bowel disease, taken at the surveillance colonoscopy before the one where dysplasia was found — a mean of 20 months earlier — and compared them with 76 biopsies from 20 patients who never developed neoplasia.

Aberrant p53 overexpression, defined as strong nuclear staining in at least 10% of epithelial cells, was found in 36% of patients who went on to dysplasia against 5% of controls, and was mostly right-sided. It was highly specific (95%) but missed most future cases (sensitivity 36%). Combining it with abnormal DNA content by flow cytometry raised sensitivity to 64%.

This is a small, retrospective study and not a validated test. But for a pathologist reporting surveillance biopsies in PSC-colitis, it suggests that a strong, patchy p53 pattern in otherwise benign mucosa may be worth mentioning to the gastroenterologist rather than ignoring.

• Be aware that strong p53 nuclear staining in at least 10% of cells in benign PSC-colitis mucosa was linked to later dysplasia.
• Pay particular attention to right-sided biopsies in PSC-colitis, where both p53 aberration and dysplasia clustered.
• Do not use a normal p53 stain to reassure; most future dysplasia had weak or normal p53.
• Consider discussing aberrant p53 in benign biopsies with the gastroenterologist as a reason for careful surveillance, not as dysplasia.

Why it matters

It suggests an existing stain might identify which PSC-colitis patients need the closest surveillance.

Don't overread it

With 45 patients and a retrospective design, these predictive values are early estimates; p53 overexpression in benign mucosa is not a diagnosis of dysplasia.

The statistics, in plain English

Specificity of 95% means a positive stain was rare in patients who never developed dysplasia. Sensitivity of 36% means about two in three future cases had no warning sign. The predictive values depend heavily on how common dysplasia is in the group tested, which here was artificially high by design.

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