Cutaneous Fungal Infections

Susan Massick, MD

OSU Dermatology

E-mail: Susan.Massick@osumc.edu

Phone: (614) 293-1707

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

Infection limited to keratin structures Stratum corneum Hair Nails

Types of Dermatophyte Infections

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 M. canis + fluorescence T. tonsurans - fluorescence

Endothrix: Spores within the hair shaft

Spores

Hair shaft

Ectothrix: Spores outside hair sheath

Spores outside hair sheath

Hair Shaft

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

Tinea capitis, corporis, cruris, pedis

Most common dermatophytes

T. tonsurans, rubrum, mentagrophytes and M. canis

Physical exam often characteristic, can confirm with KOH scraping and fungal culture

Treatment with topical/oral antifungals

Cutaneous Fungal Infections Quiz

Thank you for completing this module

• I hope that I was able to teach the subject clearly.• If you have any questions, write to me.

Susan.Massick@osumc.edu

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