Bile Duct Brush Cytology - Challenges, Limitations and Ancillary Studies

Abstract

Brush cytology of the bile duct, pancreatic duct, common bile duct and the ampulla has become an established tool in evaluating obstructive biliary strictures and masses since mid 1970s. Cytology remains the initial choice in determining the precise nature preoperatively, especially because of the unwanted complications that follow the biopsy of these lesions. Most benign strictures are managed by ductal dilatation or stenting while for the malignant strictures Whipple resection or bile duct resection is undertaken when operable. Therefore, confirmation of the benign or malignant nature of the stricture is of prime clinical importance. Recognition of certain key features on cytology can help categorise these cases into suitable definitive categories and thus help the clinicians to better and timely manage patients. The cytology of the biliary tract has a high specificity, but its sensitivity is quite poor. Growing wealth of ancillary tests can be utilised with the indeterminate cytology results to facilitate patient outcome.

Diagnostic sensitivity and risk of malignancy for bile duct brushings categorized by the Papanicolaou Society of Cytopathology System for reporting pancreaticobiliary cytopathology

“…Diagnostic sensitivity for bile duct brushings has been variable with reported sensitivities ranging from 40% to 60% in the majority of studies. [10][11][12][13][14][15][16][17] Our finding of a 64% sensitivity is similar. A number of authors have attempted to define diagnostic criteria which would improve overall sensitivity with many of these updated criteria demonstrating a sensitivity of between 35% and 83%.…”

“…Prior studies have reported a risk of malignancy for the benign category of between 6% and 36%. [7][8][9][11][12][13] This risk of malignancy range is higher than that reported for the negative category in bronchial brushings. 18 This wide range and high estimates for risk of malignancy for negative bile duct brushing specimens are most likely related to the overall poor sensitivity of the brushing technique as described by Mantoo.…”

“…The wide range in estimates for ROM in the categories negative and atypical may be related to the low sensitivity of the brushing technique as reported in the literature. [11][12][13][14][15][16][17] Finally, sensitivity of the brushing technique remains poor being only 60% in our study and has been reported to be as low as 19% if only cases characterized as malignant are considered malignant for statistical purposes. 6…”

Cytology of Bile Duct Brushings: Streaming Ahead with Time

“…Diagnostic accuracy has varied but most authors have reported a sensitivity of between 30 and 60% and a specificity ranging from 90 to 100% for diagnosing maligancy (Table 2) [9][10][11][12][13][14][15][16][17][18][19][20][21][22]. Like any technique, BDB has its faults, chiefly being its low sensitivity rate.…”

“…These are some of the most challenging cytologic specimens to evaluate due in part to poor specimen quality and quantity, as well as frequent ulceration, inflammation, and stentrelated marked reactive atypia of the biliary epithelium that may make the distinction of benign or reactive biliary epithelium from neoplasms particularly challenging and result in a false-positive diagnosis of malignancy [24]. Therefore, the threshold for malignant diagnosis is generally high in BDB cytology [10]. A significant number of false-negative results may be due to the high frequency of deceptively benign-appearing carcinomas in this site e.g.…”