Tinea versicolor of the scalp

Uncommon presentations of tinea versicolor

Tinea versicolor (TV) is a common cutaneous fungal infection characterized by superficial scaling and a mild disturbance of skin pigmentation. It typically affects the chest, upper back, and shoulders. However, involvement of more unusual regions of the body such as the face and scalp, arms and legs, intertriginous sites, genitalia, areolae, and palms and soles has been reported. This report details two such cases observed at our institution: a 32-year-old woman with involvement of the popliteal fossa and a 16-year-old boy with involvement of the groin. The clinician must be aware of these variations in location and perform the appropriate diagnostic workup when lesions have the characteristic morphology of TV despite an unusual location. The etiology, pathophysiology, and epidemiology of TV are reviewed and current literature describing other instances of TV in uncommon locations is discussed.

Skin diseases associated with Malassezia species

The yeasts of the genus Malassezia have been associated with a number of diseases affecting the human skin, such as pityriasis versicolor, Malassezia (Pityrosporum) folliculitis, seborrheic dermatitis and dandruff, atopic dermatitis, psoriasis, and--less commonly--with other dermatologic disorders such as confluent and reticulated papillomatosis, onychomycosis, and transient acantholytic dermatosis. Although Malassezia yeasts are a part of the normal microflora, under certain conditions they can cause superficial skin infection. The study of the clinical role of Malassezia species has been surrounded by controversy because of their fastidious nature in vitro, and relative difficulty in isolation, cultivation, and identification. Many studies have been published in the past few years after the taxonomic revision carried out in 1996 in which 7 species were recognized. Two new species have been recently described, one of which has been isolated from patients with atopic dermatitis. This review focuses on the clinical, mycologic, and immunologic aspects of the various skin diseases associated with Malassezia. It also highlights the importance of individual Malassezia species in the different dermatologic disorders related to these yeasts.

Pityriasis versicolor

Pityriasis versicolor is a common superficial fungal infection of the skin. It is caused by Malassezia spp., which are normal human saprophytes. Under certain conditions, both exogenous and endogenous, the fungus can convert from a yeast to a pathogenic mycelial form. This alteration results in mild inflammation of the skin, and in characteristic clinical and histological changes. The taxonomy of Malassezia spp. has recently been modified to include six obligatorily lipophilic species, all of which can be found on human skin, plus one non-obligatorily lipophilic species, which only rarely colonizes human hosts.

LEARNING OBJECTIVES

At the conclusion of this learning activity, participants should be aware of the role of Malassezia in the development of pityriasis versicolor, the clinical and histological changes arising from this dermatosis, and the diagnosis and treatment of this disorder.