Primary mucosal hyperplasia of the gallbladder.

A case of primary mucosal hyperplasia of the gallbladder in a 55-year-old man is reported. Endoscopic ultrasonography demonstrated diffuse mucosal thickening of the gallbladder which was associated with anomalous union of the pancreatico-biliary duct system. Histologically, the mucosa showed villous and spongioid hyperplasia. The mucosa, which consisted of tall columnar cells that were morphologically similar to ordinary gallbladder epithelium, showed no metaplastic changes such as occurrence of mucous glands, Paneth cells, goblet cells, endocrine cells, or lysozyme immunoreactivity. These findings suggested that this disease was based on hyperplasia of ordinary gallbladder epithelium.