Table 2.

Descriptive questions on proliferative verrucous leukoplakia diagnostic criteria, grouped in a matrix format and based on topic areas, to search for evidence-based results and potential evidence gaps.

Question 1	Is the clinical course of the disease (persistent or recurrent, periodicity of recurrences) determining in the PVL diagnosis?
Question 2	To what extent is the age of the lesion decisive for the diagnosis? Do the studies provide information on the age of the lesions? (follow-up time and/or months of evolution)
Question 3	What should be the clinical appearance of the lesions to make a diagnosis of proliferative verrucous leukoplakia? Were the clinical descriptions made by the authors of the lesions included in their incorporated cohorts?
Question 4	Is it necessary for the affection of gingiva and/or palate to make the diagnosis of proliferative verrucous leukoplakia? Were the anatomical affectations per patient reported from the included cohorts?
Question 5	Is it necessary to demonstrate malignant transformation to make the diagnosis of proliferative verrucous leukoplakia? Were the malignant transformation proportions reported in the included cohorts?
Question 6	Is resistance to treatment necessary to make the diagnosis of proliferative verrucous leukoplakia?
Question 7	To what extent is sex required to make the diagnosis of proliferative verrucous leukoplakia? Was the number of females and males reported in the included cohorts?
Question 8	To what extent is age required to make the diagnosis of proliferative verrucous leukoplakia? Was the age of patients reported in the included cohorts?
Question 9	To what extent is tobacco use or its absence necessary to make the diagnosis of proliferative verrucous leukoplakia? Was number of smokers and non-smokers reported in the included cohorts?
Question 10	Is the histological study necessary for the diagnosis of proliferative verrucous leukoplakia? What should be the histological substrate required to make the diagnosis of proliferative verrucous leukoplakia? Were the histological descriptions reported by the authors of the lesions analyzed incorporated in their cohorts?