Precancerous lesions of the gallbladder mucosa.

To elucidate the morphological characteristics and the incidence of precancerous lesions of the gallbladder, 200 gallbladders removed for presumed benign diseases were examined histopathologically. Dysplastic epithelia with distinct cellular and structural atypia were graded into either mild or moderate to severe degree. Twenty-nine (14.5%) of 200 cases showed dysplasia; 5 (2.5%) was to moderate to severe degree and 24 (12%) to mild degree. Carcinoma in situ was found in 4 cases (2%) and occult invasive carcinoma in 2 cases (1%). Simple hyperplasia was seen in 54 cases (27%). Abnormal epithelia showed a male preponderance in consistent with the previous report on cancer epidemiology in Japan. Dysplasia and hyperplasia were found to have close association with chronic cholecystitis, but not with gallstones per se. It was postulated that the progression of dysplasia or carcinoma in situ into invasive carcinoma may occur in the sixties to seventies.