What causes pediatric tinea versicolor?

Updated: Jan 27, 2020
  • Author: Lyubomir A Dourmishev, MD, PhD; Chief Editor: Dirk M Elston, MD  more...
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Answer

M furfur is now the most commonly accepted name for the etiologic agent of tinea versicolor. Thus, P orbiculare, P ovale, and Malassezia ovalis are synonyms .

M furfur is a dimorphic lipophilic organism that is cultured only in media enriched with C12-sized or C14-sized fatty acids. Malassezia is able to exist in both yeast and mycelial forms, with yeast most commonly associated with saprofital form (P ovale). Historically, the name M furfur was used to designate the fungal pathogen of tinea versicolor before it is grown in culture. M furfur is not a dermatophyte, does not grow on dermatophyte test media (DTM), and does not respond to griseofulvin therapy.

With the advent of DNA sequencing, numerous pathogenic and nonpathogenic species were found. Some of them appear to be more common in certain areas of the world, and some are more likely to be pathogenic in one area and not in another. Much of the confusion was resolved with the taxonomic revision in 1996, based on sequencing of the large-subunit rRNA and nuclear DNA of more than 100 isolates of Malassezia species. [3] The genus Malassezia was revised to include 7 species: Malassezia globosa, Malassezia sympodialis, M furfur, Malassezia slooffiae, Malassezia pachydermatis, Malassezia restricta, and Malassezia obtusa. The clinical significance of each of these species is under investigation. A study of the epidemiology of Malassezia yeasts associated with pityriasis (tinea) versicolor in Canada revealed the most frequently isolated species included M sympodialis, M globosa, and M furfur.

One study found M globosa in 97% of patients with tinea versicolor; it was found alone in 60% of cases, was associated with M sympodialis in 29% of cases, and was associated with M slooffiae in 7% of cases. [3]  M sympodialis and M slooffiae were found in similar percentages on clinically uninvolved skin of the trunk, whereas M globosa was not isolated at other sites. Thus, some authors suggest that M globosa in its mycelial phase is the causative agent of tinea versicolor. [3, 4]


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