Incidence and pathogenesis of villous tumors of the gallbladder, and their relation to cancer.

The aim of this study was to investigate the incidence and pathogenesis of villous tumors of the gallbladder, and their relation to cancer. Five hundred and thirty-three cases of cholecystectomy and 1300 randomly selected autopsy cases, mainly elderly individuals, were investigated. Gallbladders were fixed in 10% formalin after operation or at autopsy, followed by macroscopic study. In cases of villous tumors, the entire gallbladder was cut into 5-mm-thick serial sections, embedded in paraffin, cut to 4-microns, stained with hematoxylin and eosin (H&E), and histologically studied. To investigate cancer-associated antigens, i.e., carcinoembryonic antigen (CEA) and carbohydrate antigen (CA) 19-9, deparaffinized sections were examined by the peroxidase-antiperoxidase (PAP) immunohistochemical technique with anti-CEA and anti-CA 19-9 antibodies. Villous tumor was found in two resected cases (0.38%) and in one autopsy case (0.08%). Histologically, one of the villous tumors consisted mainly of a proliferation of lining epithelia; the other two consisted mainly of a proliferation of glands. In all three cases, the patients had had accompanying chronic or acute inflammation and two were accompanied by cholecystolithiasis, which made us aware of the importance of inflammation or trauma from stones in the pathogenesis of such neoplasms. Although no apparent cancerous epithelium was observed in any of these tumors by studying H&E specimens, moderate structural and cellular atypism was found in one of them. The atypical epithelium in this case was positively stained for CEA and CA 19-9. It was concluded that villous tumor should be considered to be a premalignant lesion.