Department of Dermatology, University of Texas Southwestern Medical Centre Dallas, Texas, USA2Department of Dermatology, Maulana Azad Medical College and Lok Nayak Hospital New Delhi, India
Fungal diseases are common dermatologic complaint in medical practice. Because these conditions can manifest in many different ways, it is important to get a clear understanding of the classification, characteristics, and treatment options for these often complex disorders.
In general, common cutaneous fungal infections can be divided into broad categories; specifically, superficial fungal infections, subcutaneous fungal infections, and systemic fungal infections. It is important to note that systemic fungal infections are often referred to as “deep” infections.1
Superficial fungal infections2,3 commonly invade the stratum corneum, and include conditions such as pityriasis versicolor, tinea nigra, black piedra, white piedra, tinea capitis, tinea corporis, tines cruris, tinea manuum, tinea faciei, tinea pedis,4 and cutaneous candidiasis.
Subcutaneous fungal infections tend to result from inoculation or implantation of the causative organism. Conversely, systemic fungal infections most commonly occur from direct extension of the organism into the surrounding structures or hematogenous spread.
Of the three broad categories listed above, dermatophyte infections are some of the most common skin fungal infections seen in dermatology and non-dermatology practices. It is well-known that the most common dermatophyte infection worldwide is Trichophyton rubrum. Humans typically get infected with dermatophyte infections through human contact and would be referred to as antropophilic fungal infections, or if acquired from animal to human would be referred to as zoophilic.
A less common category is geophilic dermatophyte infections which occur from soil contact to human or animal. There are several known risk factors for the development of dermatophyte infections including household contact, sebum production, physiologic factors, and sex. In general, men more commonly get tinea pedis and tinea cruris, and postpubertal men are typically more affected by onychomycosis than women. Dermatophyte infections can have various clinical presentations, and have been known to mimic other dermatologic conditions, e.g., tinea corporis can often be mistaken for various eczematous dermatitides like nummular, atopic, and even contact dermatitis. Psoriasis, impetigo, pityriasis versicolor, and erythema annulare centrifugum are just examples of other papulosquamous conditions that can commonly be in the differential diagnosis of cutaneous fungal infections. Conversely, tinea capitis can often be mistaken for alopecia areata, trichotillomania, folliculitis, pyoderma, seborrheic dermatitis, and if extensive even scarring alopecia.
Because of the complexity and nuances in the diagnosis and management of cutaneous fungal infections, the articles and topics included in this text have been designed with the hope that clinicians will find practical pearls to better aid in the treatment of their patients.5
- Elewski BE, Sobera J. Fungal disease. Dermatology. 2008;1:1135–63.
- Assaf RR, Weil ML. The superficial mycoses. Dermatol Clin. 1996;14:57–67.
- Elewski BE, Hazen PG. The superficial mycoses and the dermatophytes. J Am Acad Dermatol. 1989;21:655–73.
- Leyden JJ, Aly R. Tinea pedis. Semin Dermatol. 1993;12:280–4.
- Smith EB. The treatment of dermatophytosis: safety considerations. J Am Acad Dermatol. 2000;43:S113–19.