Can DNA cytometry be used for evaluation of malignancy and premalignancy in bile duct strictures in primary sclerosing cholangitis?

Background/Aims: The significance of DNA ploidy determinations for diagnosing cholangiocarcinoma (CC) in primary sclerosing cholangitis (PSC) has not previously been evaluated. Knowledge of tumour cell ploidy by DNA cytometry may facilitate the evaluation of malignant and premalignant lesions in PSC. Methods: Twenty-eight patients with CC were studied; 10 of the patients had PSC. Seventeen samples from 15 patients with PSC but without CC were used as controls for benign strictures. Gallbladder tissue from 100 patients with chronic cholecystitis was also analysed. DNA was measured using flow cytometry on cells from paraffin-embedded tissues. Results: Tumours from patients with PSC displayed non-tetraploid DNA aneuploidy significantly more often (80%) than tumours from patients without PSC (39%) (p<0.05). CC from patients with PSC significantly more often displayed DNA aneuploidy: 80% (8/10) compared with 12% (2/17) in bile ducts in PSC without CC (p=0.0007). The frequency of DNA aneuploidy in gallbladder tissue from patients with chronic cholecystasis was 1% (1/100). Conclusion: The high prevalence of DNA aneuploidy in PSC-related CC and the low prevalence in benign PSC strictures point to DNA cytometry as a possible future method for detecting malignant and premalignant changes in bile duct strictures in patients with PSC. This method may be useful in selecting PSC patients for liver transplantation.