Carcinoma of extrahepatic bile ducts. A histopathologic study.

The material consisted of 44 primary carcinomas of the extrahepatic bile ducts. It was possible to investigate the border region in 15 specimens, 12 (80%) of which showed metaplastic changes. All of these specimens had dysplastic changes in superficial epithelium, often multifocal: mild dysplasia in 91% of cases, moderate in 82% and severe in 45%; and dysplastic changes in the lower glandular epithelium: mild dysplasia in 57% of cases, moderate in 57% and severe in 14%. Of the 44 carcinomas, 16 were papillary adenocarcinomas and 28 gland-forming adenocarcinomas. The material included no mucinous carcinoma nor adenosquamous carcinoma or squamous cell carcinoma. According to their degree of differentiation, the tumours were graded in three groups. The criteria were the same as in the study of carcinoma of the gallbladder (Laitio, manuscript). The luminal surface of the tumour was present in 31 cases. In 17 (54.8%) cases, the structure was intestinal containing goblet cells (group I). In 18 of the 31 cases dedifferentation was apparent in the deeper parts. In the superficial parts there was no anaplastic carcinoma (group III). The histochemical results was similar to that in the gallbladder. The morphologically normal epithelium contained sulphated mucin. The metaplastic and the tumorous areas contained mainly non-sulphated acid mucin and neutral mucin. These results show that the cancerogenesis was similar to that in the gallbladder. Dysplastic changes develop in metaplastic cells and become malignant. Often, the forming of the intestinal tumour structure, as it undergoes changes, finally attains an anaplastic structure.