Histopathological and immunophenotypical features of intestinal-type adenocarcinoma of the gallbladder and its precursors.

BACKGROUND Intestinal-type adenocarcinoma of the gallbladder is an unusual malignancy associated with low- and high-grade intraepithelial neoplasms. The literature on the clinicopathologic characteristics of the precursor lesions of gallbladder cancer is limited, due in part to the variability in its definition and terminology. METHODS Here we report one case of intestinal-type adenocarcinoma of the gallbladder with distinctive morphology and associated precursor lesions. All of the hematoxylin and eosin stained slides were reviewed. Immunostains were performed using the avidin-biotin complex method for CK20, CK7, CDX2, MUC1, MUC2, and MUC-5AC. We also reviewed the literature discussing the current terminology from the World Health Organization for these lesions. RESULTS A 70-year-old man presented with epigastric abdominal pain and bloating. Computed tomography demonstrated a large heterogeneous gallbladder mass. Macroscopically, the gallbladder was 7.5 x 5.5 x 4.5 cm with smooth serosa. The lumen was occupied by a 5.0 x 4.5 x 3.0 cm irregular friable exophytic mass. The remaining mucosa had a tan brown to pink color with granular/papillary excrescences of up to 0.7 cm in thickness. Histologically, the tubulopapillary adenoma was lined by pseudostratified columnar epithelium with low and extensive high-grade dysplasia. Goblet cell and cystic dilatation were present in some glands. Immunohistochemistry showed that the intestinal type was positive for CK20, CK7, and CDX2, focally positive for MUC1/2, and negative for MUC-5AC. CONCLUSION This case showed the complete spectrum of the progression of intestinal-type intracholecystic papillary-tubular neoplasms of the gallbladder.