Background: For the early diagnosis of malignant biliary stricture due to biliary-pancreatic carcinoma, conventional biliary brush cytology with endoscopic retrograde cholangiopancreatography (ERCP; the conventional method) is not sensitive enough.
Methods: Two hundred nine patients with biliary stricture who were admitted between September 2015 and June 2020 were enrolled in this study. Biliary brush cytology was performed on all patients. Samples were diagnosed independently by an expert pathologist and medical doctor with conventional cytology and photodynamic diagnosis (PDD) with 5-aminolevulinic acid.
Results: The definitive diagnoses were 49 benign and 160 malignant diseases. The conventional method had a sensitivity of 77.5% (124/160) and specificity of 100% (49/49). The PDD method had a sensitivity of 77.5% (124/160) and specificity of 67.3% (33/49). The conventional method identified 36 malignant diseases as false negatives, while the PDD method enabled successful diagnoses of malignant diseases in 19 of these 36 patients. When PDD was combined with the conventional method, the sensitivity significantly increased to 89.4% (143/160, P = 0.006), and for biliary tract diseases only, the sensitivity increased to 95.6% (88/92, P = 0.001).
Conclusions: Malignant biliary stricture can be diagnosed effectively and safely with the in vitro PDD method. The sensitivity could be further increased by combining PDD with the conventional method.
Keywords: Aminolevulinic acid; Bile duct neoplasms; Biliary stricture; Cytology; Photodynamic diagnosis.
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