Malassezia species in skin diseases.

Since the taxonomic revision carried out in 1996, enlarging the genus Malassezia to comprise seven different species, a number of studies have investigated from different points of view -- mycological, molecular and immunological -- the relationships of these species with the pathologies associated with lipophilic yeasts, as well as its presence in healthy skin. From these studies, it now appears clear that Malassezia globosa is the main species associated with pityriasis versicolor, which is the only cutaneous disease in which the involvement of Malassezia is undisputed. Nevertheless, this species can also be found in normal skin, in which the predominant species is Malassezia sympodialis. In the remaining dermatological disorders related to Malassezia, the role of these yeasts is controversial. In seborrhoeic dermatitis, atopic dermatitis and folliculitis, several studies have focused on the immunological aspects that could explain the pathogenic mechanism. In other diseases, such as confluent and reticulate papillomatosis, neonatal pustulosis, otitis and onychomycosis, the presence or significance of Malassezia is still a matter of dispute.