A 50-year-old woman with primary sclerosing cholangitis (PSC) develops a dominant stricture. CA 19-9 is markedly elevated at 1200 U/mL. What additional investigation is MOST useful to differentiate malignant stricture from dominant benign stricture in PSC?

• A Repeat MRCP in 3 months
• B EUS-guided FNA of the biliary stricture
• C PET-CT scan to identify metabolically active tissue
• D ERCP with brush cytology and fluorescence in situ hybridisation (FISH) for chromosomal polysomy ✓

Explanation

In PSC patients with a dominant stricture and elevated CA 19-9, ERCP with biliary brush cytology supplemented by FISH (fluorescence in situ hybridisation) for chromosomal polysomy (gains at 1q21, 7p12, 8q24, 9p21) significantly improves sensitivity for cholangiocarcinoma detection beyond routine cytology alone (FISH sensitivity ~40-60% vs cytology ~20-30%). PET-CT has moderate sensitivity and specificity in PSC-associated cholangiocarcinoma. EUS-FNA is useful for periductal/hilar mass lesions but less applicable to intraductal strictures.

Reference: Bailey & Love's Short Practice of Surgery, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.