Biliary papillomatosis and new ultrasound imaging modalities

Biliary papillomatosis (BP) is a rare disorder of the biliary tract with a significant risk of malignant transformation and a high recurrence rate after operation due to the diffuse distribution of the disease. Preoperative diagnosis is difficult also by reasons of the low sensitivity and specificity of conventional ultrasound (US), computed tomography (CT), magnetic resonance imaging (MRI), endoscopic retrograde cholangiography (ERC) and positrone emission tomography (PET). Therefore, the introduction of new diagnostic imaging methods is of importance to improve the preoperative diagnosis of this originally as benign described disease which is reflected in the term of “benign papillomatosis of the biliary tree”.

In the last years we have been observing an increased number of patients with biliary papillomatosis. New sonographic imaging techniques including contrast enhanced ultrasound (CEUS), contrast enhanced low mechanical endoscopic ultrasound (CELMI-EUS) and endoscopic ultrasound elastography were applied to improve its differenzial diagnosis. Both contrast-enhanced US and contrast-enhanced EUS improve the delineation of the typically multilocular neoplastic masses from mucus and sludge in the biliary tract by proving the contrast enhancement within the neoplasia but not in mucus; this is especially true for small masses both in the dilated bile duct system and in the gall bladder. This contrast enhancing effect can be seen before and after placing a stent. EUS elastography might become helpful to differ between malignant and benign biliary tumour when the mass infiltrates within and beyond the wall and (or) causes severe stenosis.

In conclusion, contrast-enhanced ultrasound and contrast-enhanced endoscopic ultrasound differentiate sludge, non-shadowing stones and blood clots from neoplastic tissue in the biliary tract by demonstrating vascularity. Particularily, contrast-enhanced EUS provides high resolution images also of small intraductal lesions and reliably distinguishes them from sludge and mucin plugs. Visualisation of the papillary shape and multifocal nature of the wall adherent lesions supports the diagnosis of biliary papillomatosis. Endoscopic ultrasound elastography reflects and quantifies the hardness of neoplastic tissue which can be an indicator of malignant transformation.