Biliary brush cytology for the diagnosis of malignancy: a single center experience

Differentiation between benign and malignant biliary strictures is critical to the provision of adequate treatment. Brush cytology during the endoscopic retrograde cholangiopancreatography (ERCP) is the most commonly used method for obtaining tissue confirmation of the nature of biliary strictures. It's specificity is remarkably high but reported sensitivities for the diagnosis of malignancy are low. Aim of our study was to assess sensitivity and specificity of biliary brush cytology in our institution, to find out main causes of false negative diagnoses and to confirm impression that the team approach has impact on sensitivity. Gold standard for diagnosis was definitive surgical histology or adequate clinical follow up for minimum of six month. Direct smears made by cytotechnician at the endoscopy room, and stained according to Papanicolaou and May-Grünwald Giemsa (MGG) were examined for well-recognized features of malignancy on conventional smears as a part of diagnostic routine. Cytologic diagnoses were benign, atypical/reactive, suspicious for malignancy and malignant. Of 143 brushings with available definitive diagnosis 36 (25%) had malignant cytologic diagnosis and 91(63.6%) were classified as benign, 3 were atypical/reactive and 13 suspicious for malignancy with 20 "false-negative" cases. When specimens with atypical and suspicious cytology were excluded from data analysis sensitivity was 64% and specificity was 100% and when suspicious findings were taken into account as true positives sensitivity rose to 71%. We find that biliary brush cytology, although mainly depending on the skill of endoscopist, as well as the experience of the cytologist, is a valuable method for obtaining accurate tissue diagnosis of biliary strictures, thus solving eternal diagnostic dilemma: benign or malignant.