RESUMEN
BACKGROUND: Infiltrative adenosquamous carcinoma (ASC) of the extrahepatic bile duct is reported infrequently, which is an unusual variant of the ordinary adenocarcinoma. The simultaneous development of ASC and cystadenocarcinoma in the extrahepatic biliary tree is rare. In addition, the accurate preoperative diagnosis of concomitant carcinoma in the multiple biliary trees at an early stage is often difficult. Thus, awareness of the risk of the multiplicity of biliary tumors is perhaps the most important factor in identifying these cases. CASE SUMMARY: Here, we report a case of a 63-year-old female with jaundice, who was referred to Shuguang Hospital because of abdominal pain for 1 mo. An abdominal contrast-enhanced computed tomography revealed a type I choledochal cyst and intraluminal masses suggestive of adenoma of the common bile duct. In addition, a preoperative diagnosis of a concomitant Klatskin tumor and type I choledochal cyst was made. The patient underwent anti-inflammatory therapy, followed by radical surgery due to hilar cholangiocarcinoma and resection of the choledochal cyst. Examination of the surgical specimen revealed a papillary tumor of the common bile duct, which arose from the malignant transformation of a pre-existing cystadenoma. Histologic examination confirmed a special type of cholangiocarcinoma; the tumor in the hilar bile duct was an ASC, whereas the tumor in the common bile duct was a moderately differentiated cystadenocarcinoma. The patient showed rapid deterioration 8 mo after surgery. CONCLUSION: Although concomitant ASC and cystadenocarcinoma of the extrahepatic bile duct is difficult to diagnose before surgery, and the prognosis is poor after surgery, surgical resection is still the preferred treatment.