Bile Duct Cyst as Precursor to Biliary Tract Cancer

Abstract

Bile duct cysts (BDC) are rare, of uncertain origin, and occur most often in young females of Asian descent. Increasingly, BDCs are reported in the Western population, often with coexistent biliary tract cancer. The PubMed and Medline literature databases were searched for pertinent publications regarding the clinical association and molecular biological development of cancerogenesis in BDC. Reports from the last two decades were emphasized. Cancer is found in 10-30% of adults with BDC. The cancer-risk is low in childhood (<1% in the first decade), and shows a clear increase with age. Cholangiocarcinoma is the most common malignancy in BDC, and represents a 20- to 30-fold risk compared to the general population. The mean age of malignancy in BDC is 32 years (about two decades earlier than in the general population). Type I and type IV cysts show a higher cancer incidence, even after cyst excision. Pathological findings strongly suggest a hyperplasia-dysplasia-carcinoma sequence in carcinogenesis of pancreatico-biliary maljunction (PBM). Reflux of pancreatic enzymes, amylase, bile stasis, and an increased intraductal concentration of bile acids contribute to proliferative activity of bile acids in BDC. While microsatellite instability, k-ras mutations, expression of COX-2 and bcl-2, and increased telomerase activity seem to occur early; involvement of cyclin D1, beta-catenin, DPC-4/Smad4 and p53 appear later in carcinogenesis. Increased molecular knowledge substantiates the clinically related cancer-risk in BDC. Surgery remains the golden standard for treatment, relieves patients from associated complications, and interrupts the cancerous potential in BDC.