Clinical implications of serial versus isolated biliary fluorescence in situ hybridization (FISH) polysomy in primary sclerosing cholangitis

Background: Cholangiocarcinoma (CCA) is a leading cause of death in patients with primary sclerosing cholangitis (PSC). Biliary polysomy detected by fluorescence in situ hybridization (FISH) helps to identify patients with early CCA, but not all PSC patients with polysomy develop CCA. Here, we examined the features and clinical outcomes of PSC patients with serial versus isolated polysomy. Methods: All patients with PSC who underwent ≥1 endoscopic retrograde cholangiography (ERC) with FISH testing at Mayo Clinic, Rochester from 2008–2011 were identified. Patients diagnosed with CCA at the time of initial polysomy were excluded. Serial polysomy was defined as polysomy on ≥2 ERCs; isolated polysomy was defined as polysomy once followed by all nonpolysomy results. The primary outcome was the diagnosis of CCA. Results: Twenty-seven patients with polysomy and ≥1 subsequent ERC with FISH were identified. Of these, 11 (40.7%) had serial polysomy and 16 (59.3%) had isolated polysomy. CCA was more likely to be diagnosed in patients with serial versus isolated polysomy (36.4% vs. 6.3%; p =.046). Overall, four patients (36.4%) with serial polysomy and three (18.8%) with isolated polysomy underwent liver transplantation (LT), with time to LT being significantly shorter for the former (14.0 vs. 65.4 months; p =.0003). Conclusions: Biliary polysomy reverted in ≥50% of patients with PSC; this group appears to be at decreased risk of CCA compared to those with serial polysomy. Nevertheless, both groups should be followed closely, and those with serial polysomy may benefit from early LT evaluation.