Clear cell carcinomas of the gallbladder and extrahepatic bile ducts.

Although clear cell carcinomas have been described in numerous anatomic sites, their occurrence in the gallbladder and extrahepatic bile ducts (EHBD) is practically unknown. We report 10 such cases. Seven arose in the gallbladder and three in the EHBD; all patients with gallbladder tumors were females with cholelithiasis whose ages ranged from 56 to 68 years. Patients with EHBD tumors were younger (38 and 40 years of age) and had extrahepatic biliary obstruction and abdominal pain. Two patients with gallbladder carcinomas had elevated serum carcinoembryonic antigen (CEA) levels, and another without hepatic involvement had markedly elevated circulating levels of alpha-fetoprotein (AFP). Histologically, nine tumors were adenocarcinomas and one was a squamous cell carcinoma. Seven adenocarcinomas consisted of cords, sheets, nests, papillae, and trabeculae of clear cells with well-defined cytoplasmic borders. Two were composed predominantly of glands and papillary structures. The cells contained PAS-positive diastase-labile granules and were cytokeratin- and EMA-positive and immunoreactive for erythropoiesis-associated antigen. One gallbladder tumor contained areas of hepatoid differentiation, a feature described in gallbladder neoplasms only once before. These areas were AFP-positive and immunoreactive for CEA. By electron microscopy, they showed hepatoid differentiation with formation of bile canaliculi. In two gallbladder tumors, neoplastic cells contained subnuclear vacuoles reminiscent of early secretory endometrium. Foci of conventional adenocarcinoma or mucinous carcinoma were recognized in all nine tumors. The squamous cell carcinoma showed only foci of squamous differentiation with keratinization. The clear cells of this neoplasm had a trabecular and solid growth pattern. These clear cell neoplasms of the gallbladder and EHBD must be differentiated from metastatic renal cell carcinoma, based upon the presence of areas of conventional adenocarcinoma or foci of squamous differentiation since results of special stains and immunohistochemistry are similar in both neoplasms. One of the patients with EHBD carcinoma is alive and symptom-free 6 years following right hepatic lobectomy. Five patients with gallbladder tumors had direct extension into the liver and died with metastases. Two are living with metastases.