Tubular adenoma of the gallbladder with spindle cell metaplasia.

We report four cases of tubular adenoma of the gallbladder with spindle cell metaplasia. Three patients had solitary polyps in the gallbladder and the fourth had multiple (three) polyps. Only one patient who had a polyp of larger size had abdominal pain. Histologically, these tubular adenomas had characteristic morular foci composed of short spindle cells. These spindle cell components lacked intercellular bridges or cytoplasmic keratinization. Immunohistochemically, the spindle cells stained positively for one or more cytokeratins and negatively for vimentin, muscle actin and S-100 protein. Spindle cells are considered to represent the metaplastic component of the adenoma cells.