METAPLASIA AND PRECURSOR LESIONS OF GALLBLADDER CARCINOMA - FREQUENCY, DISTRIBUTION, AND PROBABILITY OF DETECTION IN ROUTINE HISTOLOGIC SAMPLES

Background. Gallbladder diseases, especially cholelithiasis, are extre mely frequent in Chile, and an increasing frequency of gallbladder car cinoma has been observed during the last decades. Hyperplastic and aty pical epithelial lesions of gallbladder epithelium have been considere d potential precursors of invasive carcinoma. The current study was de signed to study the frequency, distribution, extension, and probabilit y of routine detection of potentially preneoplastic changes of gallbla dder epithelium. Methods. Epithelial changes were histologically studi ed by mapping gallbladders obtained at elective cholecystectomy for li thiasis in 162 Chilean patients. Results. Antral-type metaplasia was f ound in 95.1% of the cases, intestinal metaplasia in 58.1%, hyperplasi a in 46.9%, dysplasia in 16%, and carcinoma in situ in 2.5%. A signifi cant association of intestinal metaplasia with hyperplasia, intestinal metaplasia with dysplasia, and hyperplasia with dysplasia was found. Hyperplasia and dysplasia were also present in four cases with carcino ma in situ. Mean extension of the lesions (percentages of the sections in which the change was observed) was antral-type metaplasia (62.7%), intestinal metaplasia (25.3%), hyperplasia (24.1%), dysplasia (15.5%) , and carcinoma in situ (9.7%). Antral-type and intestinal metaplasia were more extensive and more severe in patients older than 50 years of age. Hyperplasia was more extensive in cases in which it was associat ed with dysplasia and carcinoma in situ. Conclusions. The extension of metaplasia seems to depend in part on the age of the patients. The as sociation of intestinal metaplasia with hyperplasia and dysplasia agre es with the findings of other authors that relate metaplasia to gallbl adder cancer. The epithelial lesions are focal or partially confluent, thus a single random histologic section will detect less than one thi rd of the hyperplasias, dysplasias, and carcinomas in situ.