Proliferative verrucous leukoplakia: report of two cases and a discussion of clinicopathology.

Proliferative verrucous leukoplakia (PVL) is a recently delineated but poorly recognized form of multifocal leukoplakia that is premalignant and of unproven origin. PVL generally presents as a simple benign form of hyperkeratosis that tends to spread and become diffuse. Although slow-growing, the disease is persistent and irreversible. Clinically, PVL often presents as an exophytic wart-like form of leukoplakia that appears to be resistant to nearly all forms of therapy. PVL of the oral cavity is best-defined as a continuum of oral epithelial disease with hyperkeratosis at one end of a clinical and microscopic spectrum and verrucous carcinoma or squamous cell carcinoma at the other. The microscopic findings associated with PVL are dependent on the stage of the disease and the adequacy of the biopsy. Microscopic findings can be markedly variable. PVL is a clinicopathologic disorder that includes the microscopic entity known as verrucous hyperplasia as a component of its histopathologic progression. This article reports on two cases of PVL, describes the clinicopathology of the disease process, and presents therapeutic and etiologic considerations.