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Cutaneous Fungal Infections
Susan Massick, MD
OSU Dermatology
Learning Objectives
 Identify and diagnose cutaneous fungal
infections
 Plan treatment approaches for dermatophyte
skin infections
What are Dermatophytes?
 Dermatophytes: fungi that digest keratin
Geophilic: soil keratin
Zoophilic: animal keratin
Anthrophilic: human keratin
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Infection limited to keratin structures
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Stratum corneum
Hair
Nails
Types of Dermatophyte Infections
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Tinea Capitis
Tinea Corporis
Tinea Cruris
Tinea pedis and Onychomycosis
Tinea Versicolor
 Common genera: Microsporum, Trichophyton, and
Epidermophyton
Tinea Capitis: Scalp Ringworm
 Common fungal infection in children, especially African
American children
 Trichophyton tonsurans is most common anthrophilic
organism to cause tinea capitis in U.S.
 Microsporum canis is most common zoophilic organism
to cause tinea capitis in U.S.
Clinical Manifestations of Tinea Capitis
 Patches of alopecia with erythema and scaling
 Small black dots
 Diffuse dandruff
 Kerion formation due to severe inflammation
Physical exam: Round patchy alopecia
with mild scale
Physical exam: Black dot formation
Physical exam: Kerion
Physical exam: Diffuse scaliness
Diagnosis of Tinea Capitis
 Diagnosis can be established by KOH and fungal culture
 Wood’s lamp can identify certain dermatophytes via
fluorescence
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M. canis
T. tonsurans
+ fluorescence
- fluorescence
Endothrix: Spores within the hair shaft
Hair shaft
Spores
Ectothrix: Spores outside hair sheath
Hair Shaft
Spores outside hair sheath
Wood’s lamp with fluorescence
Treatment of Tinea Capitis
 Tinea capitis must be treated with oral therapy
 First line treatment: griseofulvin, which disrupts fungal
microtubule formation
 Other alternative oral medications include terbinafine,
fluconazole, and itraconazole
 Add shampoos, such as selenium sulfide, cicloprox, or
ketoconazole, to decrease transmissibility of infection
Tinea Corporis
 Also called ringworm
 Red scaly ring with central clearing
 May involve trunk, arms, legs, neck
Physical exam (T. corporis):
annular scaly red ring with central clearing
Tinea Corporis: Diagnosis and Treatment
 Most common fungal etiologies:
Trichophyton rubrum, Microsporum canis, and
Trichophyton mentagrophytes
 Diagnosis can be made by KOH exam
 Can treat with topical antifungals for local disease and
systemic oral antifungals, such as terbinafine or
griseofulvin, if widespread
KOH skin scraping: Fungal filaments
Tinea Cruris
 Also known as “jock itch”
 Presents as chronic brown to red patches in groin
folds and upper/inner thighs
 Rare before puberty, more common in men
 Often spares scrotum, penile shaft, glans penis
Physical exam (T. cruris): Red patch in groin
with sparing of penis and scrotum
Tinea Cruris
 Should be differentiated from candidiasis, which is
typically bright red, often involves scrotum, glans penis,
may manifest satellite pustules
 Common fungal etiologies include Trichophyton rubrum,
Trichophyton mentagrophytes, Epidermophyton
floccosum
 Usually responds to topical antifungal therapy
Tinea Pedis
 Extremely common fungal infection of skin of feet
 Commonly called “athlete’s foot”
 Similar fungal organisms that cause tinea cruris:
Trichophyton rubrum and mentagrophytes
Tinea pedis: Presentation and Treatment
 Moccasin type causes redness and scaling of soles and
sides of feet
 Interdigital type produces white macerated fissures
between the toes, usually 4th-5th spaces
 Bullous type produces small blisters on sole of foot
 Often responds to topical antifungal agents, such as
topical terbinafine
Physical exam: Moccasin type T. pedis
Physical exam: T. pedis
Onychomycosis
 Fungal infection of nails, or tinea unguium
 When toenails involved, often associated with tinea
pedis
 May produce yellow or white discoloration of toenails
with dystrophy or separation of nail from nailbed
 Nails may become thickened or develop white powder
under the nail
 Fungal etiology is similar to tinea corporis: T. tonsurans,
T. rubrum
Physical exam: Onychomycosis
Green nail: Pseudomonas infection
Treatment of Onychomycosis
 Usually requires systemic antifungal agents with
terbenafine being most effective. Itraconazole is
less effective.
 Topical antifungals are less effective
 Tinea pedis cannot be effectively treated long
term unless onychomycosis is also eliminated.
Tinea versicolor (TV)
 Due to an overgrowth of a yeast (Pityrosporum ovale),
which thrives on lipids, such as sebum
 Tinea versicolor (TV) usually presents as hypo or
hyperpigmented macules with very fine scale on upper
chest, upper back, shoulders
 Hypopigmentation is due to dicarboxylic acid produced by
the yeast, which inhibits melanin formation
Physical exam: T. versicolor
Physical exam: T. versicolor
Tinea versicolor: Diagnosis and Treatment
 Diagnosis made on physical exam and KOH scraping
with characteristic “spaghetti and meatballs” appearance
of hyphae and spores
 Treat with antifungal shampoos, such as selenium
sulfide or ketoconazole, and/or with single doses of oral
ketoconazole
Tinea versicolor: KOH scraping
Summary: Dermatophyte Infections
 Very common superficial fungal infections
 Often named for the body location targeted
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Tinea capitis, corporis, cruris, pedis
 Most common dermatophytes
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T. tonsurans, rubrum, mentagrophytes and M. canis
 Physical exam often characteristic, can confirm with KOH
scraping and fungal culture
 Treatment with topical/oral antifungals
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