Test Catalog

Test ID: FBILM    
Biliary Tract Malignancy-Cytology, FISH, Varies

Useful For Suggests clinical disorders or settings where the test may be helpful

Assessing bile duct brushing or hepatobiliary brushing specimens for malignancy

Testing Algorithm Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

When this test is ordered, FISH testing will be performed. When additional specimens are received, the laboratory will add BILMA / Biliary Tract Malignancy, FISH, Specimen A, Varies to the first specimen, BILMB / Biliary Tract Malignancy, FISH, Specimen B, Varies to the second specimen, BILMC / Biliary Tract Malignancy, FISH, Specimen C, Varies to the third specimen, and so on.

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Endoscopic retrograde cholangiopancreatography (ERCP) is used to examine patients with biliary tract obstruction or stricture for possible malignancy. Biopsies and cytologic specimens are obtained at the time of ERCP. Cytologic analysis complements biopsy by sometimes detecting malignancy in patients with a negative biopsy. Nonetheless, a number of studies suggest that the overall sensitivity of bile duct brushing and bile aspirate cytology is quite low.


Fluorescence in situ hybridization (FISH) is a technique that utilizes fluorescently labeled DNA probes to examine cells for chromosomal alterations. FISH can be used to detect cells with chromosomal changes (eg, aneuploidy) that are indicative of malignancy. Studies in our laboratory indicate that the sensitivity of FISH to detect malignant cells in biliary brush specimens is superior to that of conventional cytology.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

Negative for malignancy.

Interpretation Provides information to assist in interpretation of the test results

An interpretive report will be provided.


A positive cytology diagnosis is normally definitive for the presence of malignancy.


Suspicious or atypical results need further confirmation by clinical observation, repeat cytology, or perhaps appropriate biopsy.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

A positive FISH result does not identify location or type of malignancy. FISH abnormalities may be associated with high-grade dysplasia or carcinoma in situ. Cytology and biopsy may help clarify such situations.

Supportive Data

Cell counts using the biliary FISH probe set on pancreatobiliary brushings were compared between 49 patients with malignancy and 41 patients without malignancy to determine normal value cutoffs for this assay. The cutoff values were independently validated in a blinded study from brushing samples collected from 112 patients at the time of endoscopic retrograde cholangiopancreatography (ERCP). Among patients with malignancy on follow-up, the sensitivity of a polysomy FISH result was significantly superior to cytology (74% vs. 28%, P<0.001). The specificity of FISH and cytology were similar (96% vs. 100%).

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. Barr Fritcher EG, Voss JS, Brankley SM, et al: An Optimized Set of Fluorescence In Situ Hybridization Probes for Detection of Pancreatobiliary Tract Cancer in Cytology Brush Samples. Gastroenterology 2015;149(7):1813-1824

2. Barr Fritcher EG, Kipp BR, Voss JS, et al: The Development of a Tailored Pancreatobiliary Fluorescence in situ Hybridization (FISH) Assay to Improve Detection of Malignancy in Pancreatobiliary Brushings. J Mol Diagn 2013;15(6):909

3. Barr Fritcher EG, Kipp BR, Halling KC, et al: A multivariable model using advanced cytologic methods for the evaluation of indeterminate pancreatobiliary strictures. Gastroenterology 2009;136(7):2180-2186