Metaplastic lesions of the extrahepatic bile ducts: A morphologic and immunohistochemical study

Although metaplastic changes can occur in the extrahepatic bile ducts, a de tailed morphologic study of these lesions has not been done. We examined th e bile duct mucosa in 42 pancreadcoduodenectomy specimens, 32 with neoplast ic lesions and ten with inflammatory lesions of the extrahepatic bile ducts , to assess the prevalence and type of metaplastic lesions. For comparison, the common bile ducts from 10 autopsy cases were reviewed. Twenty of the 4 2 total cases (48%), 13 of the 32 neoplastic cases (40%), and 7 of the 10 i nflammatory cases (70%) had metaplastic changes. Pyloric gland metaplasia w as the most common type (16/20 cases; 80%), whereas intestinal metaplasia w as seen in 1/20 cases (5%). A combination of pyloric gland and intestinal m etaplasia occurred in 2/20 cases (10%), and squamous metaplasia plus the ab ove-mentioned two types of metaplasia was seen in 1/20 cases (5%). None of the normal common bile ducts obtained from ten autopsies had metaplastic ch anges. Endocrine cells were identified in nine (56%) of 17 metaplastic lesi ons. In contrast, endocrine cells within the intramural glands were seen in only 2 of the 10 normal common bile ducts. Although a significant proporti on of carcinomas (6/13 cases) was in close proximity to areas of metaplasia , we were unable to find dysplastic foci within the metaplastic glands or t he metaplastic surface epithelium. Reactive atypical cells involved the sur face biliary epithelium and intramural glands and were associated with infl ammation and metaplastic changes. The presence of goblet, mucinous, squamou s, and reactive atypical cells in association with hyperplasia of intramura l glands in frozen sections or small biopsy specimens may be mistaken for m alignancy; hence, recognition of these lesions is of diagnostic importance.