Expandable biliary metal stents for malignancies: endoscopic insertion and diathermic cleaning for tumor ingrowth. Seventeen patients with malignant biliary strictures have been treated by endoscopic insertion of self-expandable metallic prostheses. Two patients received two prostheses inserted simultaneously in both the left and right hepatic ducts for Klatskin tumor type III. Immediate results were satisfactory despite an operative mortality of 18%, and neither early nor late clogging was observed even in patients who presented previously with sludge above plastic stents that were removed. However, among five patients followed for more than 4 months, two presented with obstruction due to tumor ingrowth into the stent through the metallic mesh. Accordingly, initial enthusiasm concerning long-term patency of these stents has decreased. However, we describe a technique of "diathermic cleaning" of tumor ingrowth which can easily restore the stent patency. The advantages of these wire mesh 30 F stents are their easier insertion, better immediate drainage, and absence of dislocation or perforation. 