Yeast organisms associated with human oral leukoplakia

Oral leukoplakia is a lesion of variable clinical behaviour and a malignant transformation rate of 3-6%. Leukoplakia exhibits various histologic features, hyperkeratinization being the most consistent. As yeast organisms have been encountered in a high proportion of leukoplakia cases, a causal role has been suggested for these organisms. Candida albicans is by far the most commonly isolated yeast from leukoplakia, but also other Candida species as well as Torulopsis and Saccharomyces species may be encountered. The species composition of the mycoflora in leukoplakia does however not differ from that of normal oral mucosa. Subspecies differentiation of C. albicans has revealed the existence of different oral strains between individuals and further, strain differences of C. albicans in leukoplakia and in normal mucosa have been observed. This procedure may lead to isolation and identification of the yeast organisms causally associated with leukoplakia.