Proliferative verrucous leukoplakia of the gingiva

Objective. The purpose of this study was to describe the clinical-pathologic features of what appears to be a gingival form of proliferative verrucous leukoplakia. Study design. Ten adult patients with recurrent and histologically progressive gingival leukoplakias who were diagnosed and treated at the University of California, San Francisco between 1994 and 1999, comprised the subject group for this investigation. Clinical and microscopic features were reviewed. Proliferation indices and p53 expression were evaluated immunohistochemically and the presence of human papillomavirus (HPV) DNA was determined by using polymerase chain reaction (PCR) amplification. Results, Lesions presented as solitary or regional flat/papillary/verrucal leukoplakias of the free and attached gingiva (tooth-bearing areas only). With time, flat lesions developed a papillary or verruciform profile. Although lesions were recurrent, they were confined to the gingiva, and multiple lesions did not develop. Half the patients used tobacco, and HPV could not be detected by using PCR. Microscopically 6 cases began as hyperkeratotic lesions, and 3 initially exhibited a psoriasiform pattern with a marked inflammatory component. With recurrences, the lesions became progressively atypical histologically. The proliferation indices for these lesions showed modest increases over normal epithelium, and positive p53 staining was evident in 4 of 10 cases, indicating a disruption of the keratinocyte cell cycle in these lesions. The mechanism associated with the positive p53 staining (protein binding to wild type p53 versus mutation of the p53 gene) was not determined. Lesions recurred after conservative scalpel or laser excision, and many developed into verrucous or squamous cell carcinoma. Conclusions, Proliferative verrucous leukoplakia of the gingiva (PVLC) appears to be a subset of oral proliferative verrucous leukoplakia. It can be characterized as a solitary, recurring, progressive white patch that develops a verruciform architecture and may not be associated with HPV. PVLC has an unpredictable course and is at risk for development into verrucous or squamous cell carcinoma. Currently there is no way to determine or predict which gingival white lesions will follow the clinical course described for this group of patients with PVLG.