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The main etiology of bile duct strictures closely related to the liver is a malignancy, but the differentiation of benign and malignant strictures is notoriously difficult.

The main etiology of bile duct strictures closely related to the liver is a malignancy (cancer). However, the differentiation of benign and malignant strictures is notoriously difficult. The consequences for the patient are considerable because cancer in this anatomical location requires extensive surgery with removal of a large part of the liver. Extensive work-up including multi-slice computed tomography (CT), colour Doppler ultrasonography and magnetic resonance imaging (MRI) may improve the diagnostic dilemma. However, up to date, no single investigation reliably differentiates malignant from benign bile duct strictures.

A research article to be published on August 28, 2008 in the World Journal of Gastroenterology addresses this question. The research team led by Prof. van Gulik from the Surgical Department, analyzed a patient cohort that underwent resection for presumed malignancy of the bile duct, during the period 1998 to 2006. The final histologic diagnosis of 68 patients was correlated with the preoperative clinical, laboratory and radiological findings. Fifteen percent patients were found to have a benign lesion. The findings of the different imaging studies revealed that only one feature, ie involvement of the blood vessels, showed a significant association with malignany. All other features including clinical presentation, laboratory tests, brush cytology, and other imaging studies were unable to differentiate malignant and benign strictures.

Invasion of the blood vessels was based on the findings of colour Doppler ultrasonography defined as an increase of flow compatible with stenosis, or absence of flow compatible with occlusion. Furthermore, vascular involvement was identified on contrast enhanced CT as vascular stenosis or occlusion of the portal vein and/or the hepatic artery. In 21 patients, the portal vein and/or branches of the hepatic artery were involved in the tumor process, and all these patients were finally diagnosed to have a malignant lesion.

Despite using recent, state-of-the-art imaging modalities, 15 per cent patients with presumed malignancy underwent an extensive operation but were ultimately diagnosed to have benign strictures. Due to the relatively low incidence of vascular involvement (31 per cent in this series), the absence of this finding is not conclusive. The article demonstrates that the differentiation of bile duct strictures remains difficult and that more research is needed to solve this diagnostic problem.