Urothelial leukoplakia: new aspects of etiology and therapy.

We describe 3 women in 1 family who had systemic urothelial leukoplakia with no underlying pathological condition of the urinary tract. Irritative clinical symptoms resolved, and the macroscopic and microscopic appearance improved after 6 months of therapy with sodium pentosanpolysulfate. Electron microscopy showed special cells in the basal layer of the cornified squamous epithelium that also have been found in the trigone of women with so-called squamous metaplasia. Their similarity to Merkel's cells of the skin supports the theory that ectodermal cells are misplaced during embryogenesis. Genetic factors and sex hormones seem to influence the development of certain variants of squamous epithelium within the urinary tract.