Fungal Skin Infections The 5 Minute Pediatric Consult


	Fungal Skin Infections (Dermatophyte Infections, Candidiasis, and Tinea Versicolor)

William R. Graessle and Jill A. Foster

Database
Differential Diagnosis
Data Gathering
Physical Examination
Laboratory Aids
Therapy
Follow-Up
Common Questions and Answers
Bibliography

DATABASE

DEFINITION

Superficial mycoses (fungal infection) involving the skin, hair, or nails

ETIOLOGY

Dermatophyte infections
- Tinea capitis: greater than 90% Trichophyton tonsurans in North America; Microsorum canis a predominant organism in other geographic regions
- Nonhairy sites: M. canis, T. tonsurans, T. rubrum, M. audouinii
Candidiasis: usually Candida albicans
Tinea versicolor: Malassezia furfur (also called Pityrosporum ovale)

PATHOPHYSIOLOGY

Fungal elements penetrate skin, hair shaft, or nail.
Predisposing factors may include moisture, macerated skin, and immune compromise.
Fungistatic fatty acids in sebum after puberty may offer protection against tinea capitis.
Host immune response is usually able to contain infection.
Inflammatory response is variable; highly inflammatory forms may lead to pustular lesions and kerion (a large inflammatory mass) formation.

GENETICS

Frequency and severity of infection are possibly determined by unclear genetic factors.
Increased glycogen granules in the normal skin of patients with tinea versicolor suggests an underlying disorder or genetic predisposition.

EPIDEMIOLOGY

Dermatophyte infections
- Etiology varies by geographic region.
- Tinea capitis is most common in prepubertal children.
- Tinea corporis is usually seen in younger children; tinea cruris, tinea pedis, and onychomycosis are uncommon in preadolescent children.
- Fomites and pets may be a source of infection.
Candidiasis: vast majority of infants colonized with C. albicans.
Tinea versicolor: usually seen in adolescents and young adults

COMPLICATIONS

Dermatophyte infections
- Secondary bacterial infection (which may obscure the diagnosis of dermatophyte infection)
- Kerion may lead to scarring alopecia.
Candidiasis
- Scarring in severe disease
- Fungemia in immunocompromised host

DIFFERENTIAL DIAGNOSIS

Dermatophyte infections
- Dermatologic conditions
  - Tinea capitis: seborrheic dermatitis, psoriasis, alopecia areata, trichotillomania, folliculitis, impetigo
  - Tinea corporis: herald patch of pityriasis rosea, nummular eczema, psoriasis, contact dermatitis, tinea versicolor, granuloma annulare
- Systemic diseases: cutaneous T-cell lymphoma, histiocytosis, primary skin cancer, sarcoid
Candidiasis
- Dermatologic conditions: contact dermatitis, seborrheic dermatitis, atopic dermatitis, bacterial infection
- Systemic diseases: acrodermatitis enteropathica, histiocytosis
Tinea versicolor
- Dermatologic conditions: pityriasis alba, postinflammatory hypopigmentation, vitiligo, seborrheic dermatitis, pityriasis rosea

PROGNOSIS

Relapses and recurrences are not uncommon.
Areas with a significant inflammatory component may lead to scarring and permanent alopecia.

DATA GATHERING

HISTORY

Onset is usually gradual, except for candidal diaper rash, which is often abrupt
Usually pruritic

PHYSICAL EXAMINATION

Dermatophyte infections
- Tinea corporis
  - Skin lesions usually annular, hence the term ringworm
  - May be flesh-colored, erythematous, or violet to brown
  - Highly inflammatory forms may be frankly pustular.
- Tinea capitis may have various presentations:
  - Round to oval patches of alopecia with erythema
  - Seborrheic dermatitis-like pattern with minimal or no alopecia
  - Follicular pustules with crusting, resembling bacterial folliculitis
  - Boggy, tender plaque with follicular pustules (kerion)
  - Diffusely, dry scalp
- Onychomycosis
  - White, yellow, or silvery discoloration of lateral border or distal portion of nail
  - Nail eventually becomes discolored, thickened, and deformed.
  - Affects toes more often than fingers
Candidiasis
- Diffuse erythema (often “beefy” red)
- Raised edge with a sharp margin
- Pustulovesicular, satellite lesions
- Prefers dark, warm, moist environments; favors skin folds/creases (axillae, groin, below the breasts, and in infants, the diaper area)
Tinea versicolor
- Scaling, oval macular patches
- Hypopigmented or hyperpigmented, depending on sunlight exposure and complexion
- Distributed on upper trunk, neck, and proximal arms (high amount of sebum and free fatty acids which the organism requires); occasionally occurs on the face

LABORATORY AIDS

TESTS

Diagnosis is usually made by characteristic lesions; if in doubt, may do Wood’s lamp examination, potassium hydroxide (KOH) preparation, or fungal culture.

Wood’s Lamp Examination (Short-Wave Ultraviolet Light)

Examine in a completely darkened room.
Dermatophytes: Hair infections caused by Microsporum species will give a green fluorescence; not helpful for skin or nail infections.
Tinea versicolor: yellow, coppery-orange, or bronze fluorescence.

KOH Preparation

Clean the site with alcohol.
Scrape the lesion along the scaling edge with a blade; obtain material from hair follicles and crusts.
Place material on glass slide with one drop of 10% KOH.
Warm the slide gently or let it sit for 30 minutes.
Place a cover slip on the slide.
Examine the slide under the microscope at low power under low light.

Results

Dermatophytes: arthrospores around or within hair shaft; long branching hyphae for skin infections
Candidiasis: budding yeast, pseudohyphae
Tinea versicolor: hyphae and spores (“spaghetti and meatballs”)

Fungal Culture

Obtain a specimen with scalpel blade or sterile toothbrush as described above.
Results are available in several weeks.
Some laboratories offer susceptibilities in addition to identification of fungus.
It may be difficult to distinguish normal skin colonization from infection.

THERAPY

DRUGS

Dermatophyte Infections

Tinea capitis
- First-line: Griseofulvin 15 to 20 mg/kg once daily, taken with high-fat food (e.g., milk or ice cream) for 6 to 12 weeks; concomitant therapy of 2.5% selenium sulfide shampoo twice weekly will suppress viable spores and decrease spread.
- Second-line: oral itraconazole 3 to 5 mg/kg once daily for 4 to 6 weeks.
- Kerion: Treat as tinea capitis; may require oral steroids if significant inflammation present
Tinea corporis
- Drug of choice: topical imidazole applied twice daily for 2 to 4 weeks.
- Oral therapy may be used for persistent or extensive involvement.
Onychomycosis
- Griseofulvin orally for 6 to 18 months (6 months for fingernails and 12–18 months for toenails)
- Itraconazole in weekly pulses for 3 to 4 months is effective; 200 mg twice daily for 7 days, then off for 3 weeks.

Candidiasis

Topical nystatin three to four times daily for 7 to 10 days

Tinea Versicolor

Selenium sulfide 2.5% applied to the affected skin for 10 minutes. Wash off thoroughly. Monthly applications may help prevent recurrences.
Topical imidazoles are effective but more expensive.
Oral ketoconazole 200 to 400 mg/d for 5 to 10 days, or itraconazole 200 mg/d for 5 to 7 days may be used if extensive, recurrent, or persistent.

POSSIBLE CONFLICTS WITH OTHER TREATMENTS

Many antifungals have drug interactions. Consult a reference (e.g., Physician’s Desk Reference) when prescribing them to a patient already on medication.

FOLLOW-UP

WHEN TO EXPECT IMPROVEMENT

Dermatophyte: Inflammation should improve within several days, but may take several weeks to completely resolve; nail infections may take 6 to 12 months to show improvement.
Candidal skin lesions improve within 24 to 48 hours and resolve by 1 week.
Tinea versicolor may take weeks to improve; repigmentation may take months and requires exposure to sunlight.

SIGNS TO WATCH FOR

Watch for signs of secondary bacterial infection.
Highly inflammatory lesions may require systemic steroids.

PREVENTION

Children should be discouraged from sharing clothing (especially hats).
Hair utensils and hats should be washed in hot, soapy water at the onset of therapy.
Pets should be watched and treated early for any suspicious lesions.
Isolation of the hospitalized patient is not necessary.

PITFALLS

Tinea capitis requires systemic therapy.
Application of topical steroids will decrease inflammation and may mask infection (“tinea incognito”). Use only mild steroids, if necessary.
Repeated infection may indicate a source that needs to be diagnosed and treated (e.g., family member or pet).

COMMON QUESTIONS AND ANSWERS

Q: When is oral therapy indicated for the treatment of dermatophyte infections?
A: Topical therapy is usually effective for infections of the skin; however, it penetrates hair and nails poorly. Tinea capitis and onychomycosis require oral therapy. Disease that is persistent and not responding to topical antifungals, or extensive disease, which makes topical application impractical, are also indications for systemic therapy.

Q: What is the role of topical and systemic steroids in the treatment of dermatophyte infections?
A: Topical corticosteroids may be helpful with antifungal therapy to reduce inflammation. Only mildly potent steroids should be used. Combination products containing a potent corticosteroid and an antifungal should be avoided, especially in the diaper area, where absorption may be increased.

Q: What can be done to prevent recurrent tinea versicolor in an adolescent?
A: M. furfur is a ubiquitous organism and is present on the skin of postpubertal individuals. Humid environments, excessive sweating, and unclear genetic factors result in infection. Recurrences are common and can be prevented by monthly application of selenium sulfide 2.5%.

ICD-9-CM

Dermatophyte 110.9
Candidiasis 112.9
Tinea Versicolor 111.0

BIBLIOGRAPHY

Friedman A. Superficial bacterial and fungal infections of the skin. Adv Pediatr Infect Dis 1990;5:205–219.

Goldgeier M. Fungal infections of the skin, hair and nails. Pediatr Ann 1993;22:253–259.

Rosenthal J. Pediatric fungal infections from head to toe: what’s new? Curr Opin Pediatr 1994;6:435–441.

Smith M. Tinea capitis. Pediatr Ann 1996;25:101–105.

Suarez S. New antifungal therapy for children. Adv Dermatol 1997;12:195–209.

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