Proliferative verrucous leukoplakia and its related lesions

Proliferative verrucous leukoplakia (PVL) is a unique type of clinical oral leukoplakia. Enigmatic in etiology, PVL behaves in a far more aggressive f ashion than other forms of leukoplakia. Its aggressiveness relates not only to a high recurrence rate, but more so to, a very high level of and relent less progression from a localized simple keratosis to extensive oral diseas e and squamous carcinomas of verrucous, or conventional squamous cell type. Diagnosis is often late in the protracted course of PVL with the disease i n an advanced stage when it is especially refractory to treatment. Within t he histologic spectrum that is seen in PVL, usually as a function of time, are: (1) verrucous hyperplasia (VH), a histologically defined lesion; (2) v arying degrees of dysplasia; and (3) three forms of squamous cell carcinoma : verrucous, conventional and, according to some, papillary squamous cell c arcinoma. Each of these are discussed both within and outside the context o f PVL. VH is a forerunner of verrucous carcinoma and the transition is so c onsistent that the hyperplasia, once diagnosed, should be treated like verr ucous carcinoma. VH is not only an oral lesion; it can occur in the upper a irway (sinonasal tract and larynx) where it is not usually found within a m aternal soil of PVL. Papillary squamous cell carcinoma has been a loosely d efined neoplasm, more often considered a verrucal type of malignancy. It no netheless is a distinct clinicopathologic entity, separate from verrucous c arcinoma and without a predilection for the oral cavity or an association w ith PVL. (C) 1999 Elsevier Science Ltd. All rights reserved.