[371] Biliary Stent-Related Atypia Can Be Reliably Distinguished from Adenocarcinoma on Common Bile Duct Brushings Using a Limited Number of Cytologic Features

Jonathon E Heath, Jamila R Arsala, Lindsay B Goicochea, Paul N Staats. University of Maryland Medical Center, Baltimore, MD

Background: Although it is widely accepted that cytologic atypia secondary to biliary stent is a potential pitfall in pancreatobiliary exfoliative cytology, no systematic study has been undertaken to identify the cytologic features that best distinguish these entities.
Design: A retrospective search of our archives for a four year period revealed 14 cases of bile duct brushings with biliary stents classified as either atypical or suspicious for malignancy, each with greater than 6 months of benign clinical follow-up. 15 comparison cases of bile duct brushings classified as positive for malignancy with histologic confirmation of adenocarcinoma were also identified. Cytologic features such as nuclear enlargement, nuclear contour, nuclear overlap, chromatin distribution, N/C ratio, anisonucleosis (3x size variation), mitoses, acute inflammation, disorganization, necrosis, prominence of cell borders, presence of single atypical cells, and of two distinct cell populations were assessed on Papanicolaou-stained conventional smears and liquid-based preparations. Fisher's exact test was used to determine statistical significance.
Results: We identified 5 cytologic features which achieved statistical significance: anisonucleosis (p=0.0422), atypical single cells (p= 0.0001), and two distinct cell populations (p= 0.0007) each favored malignancy, while distinct cell borders (p= 0.0018) and acute inflammation (p= 0.0035) favored benign. No other feature was statistically significant. Using a simple diagnostic algorithm incorporating only these 5 features, we were able to correctly classify 12/14 benign and 15/15 malignant cases, with a sensitivity of 88.2%, a negative predictive value of 85.7% and a specificity and positive predictive value of 100% each. In addition, on blinded review of the same cases with a focus on these criteria and enforcing a binary diagnostic classification, we correctly classified 13/14 benign and 14/15 malignant cases.
Conclusions: By using a combination of 3 markers of malignancy and 2 favoring benignity, we were able to correctly classify 27 of 29 cases. These findings suggest that most bile duct brushings from patients with biliary stents can be definitively and correctly classified as either benign or malignant using a combination of features including anisonucleosis, single atypical cells, binary cell population, distinct cell borders, and acute inflammation. Collection of additional cases to serve as a validation set is ongoing.
Category: Cytopathology

Tuesday, March 20, 2012 9:30 AM

Poster Session III # 66, Tuesday Morning

 

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