Co-expression of gastric and biliary phenotype in pyloric-gland type adenoma of the gallbladder: Immunohistochemical analysis of mucin profile and CD10

Abstract

Pyloric-gland type adenoma of the gallbladder is formed by proliferation of glands resembling pyloric glands, morphologically. No previous report has described the cellular phenotype and differentiation of pyloric-gland type adenoma of the gallbladder, using CD10 as a marker of proper biliary phenotype. Immunostainings were performed for mucin markers such as MUC5AC, human gastric mucin (HGM) for gastric foveolar type epithelium, MUC6, M-GGMC-1 for pyloric-gland type and MUC2 for intestinal goblet-cell type, and for CD10 as a proper biliary type marker on 58 pyloric-gland type adenomas of the gallbladder, as well as for p53, Ki-67 and CDX2. The percentage (X) of reactive cells in relation to the total number of tumor cells was estimated semi-quantitatively, and divided into four categories: X=0% (negative), 0% <30%, and X≥30%. CDX2 expression was considered to be positive when the percentage of positively stained cells was ≥10%. Out of the 58 pyloric-gland type adenomas, ≥30% of adenoma cells were positive for MUC5AC in 22 (38%) tumors, HGM in 29 (50%), MUC6 in 58 (100%), M-GGMC-1 in 54 (93%), MUC2 in none (0%), and CD10 in 20 (34%). MUC6 (P<0.001) and M-GGMC-1 (P<0.001) mucins were detected more frequently in pyloricgland type adenomas, and CD10 expression was significantly decreased, compared with normal gallbladder epithelium (P=0.006). P53 overexpression was not found in any of the 58 tumors, including two adenomas with carcinomatous foci.