cancerous changes than homogeneous leukoplakias. Proliferative verrucous leukoplakia Proliferative verrucous leukoplakia (PVL) is a recognized high risk subtype of non-homogeneous leukoplakia. It is uncommon, and usually involves the buccal mucosa and the gingiva (the gums). This condition is characterized by (usually) extensive, papillary or verrucoid keratotic plaques that tends to slowly enlarge into adjacent mucosal sites. An established PVL lesion is usually thick and exophytic (prominent), but initially it may be flat. Smoking does not seem to be as strongly related as it is to leukoplakia generally, and another dissimilarity is the preponderance for women over 50. There is a very high risk of dysplasia, transformation to squamous cell carcinoma with high mortality (PVL does not transform into verrucous carcinoma, which is a lesion with a good prognosis usually; the similarity of names does not reflect the common origin, but only the resemblance of their appearance). Erythroleukoplakia Erythroleukoplakia (also termed speckled leukoplakia, erythroleukoplasia or leukoerythroplasia) is a non-homogeneous lesion of mixed white (keratotic) and red (atrophic) color. Erythroplakia (erythroplasia) is an entirely red patch that cannot be attributed to any other cause. Erythroleukoplakia can therefore be considered a variant of either leukoplakia or erythroplakia since its appearance is midway between. Erythroleukoplakia frequently occurs on the buccal mucosa in the commissural area (just inside the cheek at the corners of the mouth) as a mixed lesion of white nodular patches on an erythematous background, although any part of the mouth may be affected. Erythroleukoplakia and erythroplakia have a higher risk of cancerous changes than homogeneous leukoplakia. Sublingual keratosis Sometimes leukoplakia of the floor of mouth or under the tongue is called sublingual keratosis,. though this is not universally accepted to be a distinct clinical entity from idiopathic leukoplakia generally, as it is distinguished from the latter by location only. Usually sublingual keratoses are bilateral and possess a parallel-corrugated, wrinkled surface texture described as "ebbing tide". Candidal leukoplakia Candidal leukoplakia is usually considered to be a largely historical synonym for a type of oral candidiasis, now more commonly termed chronic hyperplastic candidiasis, rather than a subtype of true leukoplakia. However, some sources use this term to refer to leukoplakia lesions that become colonized secondarily by Candida species, thereby distinguishing it from hyperplastic candidiasis. Oral hairy leukoplakia Oral hairy leukoplakia is a corrugated ("hairy") white lesion on the sides of the tongue caused by opportunistic infection with Epstein-Barr virus on a systemic background