March 1996
MIAMI BEACH, Fla.—When it comes to fungal infections, pediatricians may have trouble making the right call.
"Fungal infections of the scalp and face are underdiagnosed, and fungal infections of the feet are overdiagnosed," according to William L. Weston, MD, a Pediatric Dermatologist, who spoke here at the fifth annual Masters of Pediatrics meeting.
Tinea capitis, he said, is epidemic and produces many different lesions. "Keep a high index of suspicion for this infection. Tinea pedis and onychomycosis are overdiagnosed," said Weston, Chairman and Professor, Department of Dermatology, University of Colorado Health Science Center, Denver.
Atypical tinea capitis
Making a diagnosis of tinea capitis is more difficult when the infection presents atypically. Some of these atypical presentations include black dot and blond dot ringworm, alopecia areata-like black dot ringworm, diffuse scaling tinea capitis, multiple scalp pustules, seborrheic dermatitis or eczematous pattern tinea capitis, and tinea capitis with papular eczema.
Black dot ringworm presents with round areas of hair loss. Hairs are broken off at the follicular orifice by Trichophyton tonsurans.
Blond dot ringworm presents in the same fashion as black dot. Alopecia areata-like ringworm is characterized by multiple circles of scalp hair loss as a result of T tonsurans infection. Lymphadenopathy is an important clue.
Diffuse scaling is another form of tinea capitis and presents as fine white scales throughout the scalp.
Multiple scalp pustules is a type of tinea capitis that presents with scattered small scalp pustules. It may be mistaken for "oil folliculitis" from hair preparations. T tonsurans is the offending organism, he said.
Seborrheic dermatitis with eczematous patterns presents with disruption of skin surfaces, erythema, and scaling. Moist crusts are also seen.
Multiple kerion pattern tinea capitis presents with boggy masses in the scalp and hair loss. Superficial pustules may be seen, and lymphadenopathy is always present. "Any dermatophyte can cause kerion, but multiple kerions are usually due to T tonsurans," Weston said.
Tinea capitis with papular eczema is usually seen in the kerion stage and usually presents as multiple flat-topped papules on the forehead. The condition is thought to be the result of a hypersensitivity to the organism, he said.
Diagnosing tinea capitis
Making the diagnosis of tinea capitis calls for the correct approach.
"The Wood's lamp examination does not work, and none of the strains of T tonsurans are fluorescent. Dermatologists generally get a 67% positive rate on [potassium hydroxide] KOH examination. Pediatricians get a 33% positive rate, plus lots of false-positives," he said.
He suggests scraping hairs at the margin of the hair loss or scraping the pustules.
"Infected hairs are loose in the follicle and come out with gentle scraping. Plucking hairs usually misses the organisms, and if the hair is long enough to grasp, it probably isn't infected," he said.
Culture
Weston noted that fungal cultures remain the gold standard for diagnosis. Obtaining a good sample, however, can be a problem. He suggests using a curet to scrape the scalp surface and inoculate into agar medium or a moistened gauze to rub the hair and obtain a sample.
Atypical tinea faciei
All forms of tinea faciei should be considered atypical because they rarely are suspected, Weston said. "They can present like a lupus erythema (LE) malar rash, annular lesions of the eyelid or eye brow, or multiple lesions of the face.
"In the LE-like malar rash, there are often red, scaly areas on the nose and cheeks, which are often mistreated with topical or systemic steroids," he said.
"The usual organisms responsible for tinea faciei are Microsporum canis from dogs and cats and Trichophyton verrucosum from horses or cattle. These organisms do not fluoresce," he said. Tinea faciei can easily occur if a child holds a kitten or puppy up to the face.
Annular lesions of the eyelid or eyebrow are asymmetrical and are usually mistaken for eczema or contact dermatitis.
Tinea
corporis
Atypical forms of tinea corporis include presentations that are diaper dermatitis-like or inflammatory throughout and pustular. Other presentations include lesions that form as incomplete circles or crusted lesions, he said.
The diagnosis of tinea corporis is made from fungal cultures and KOH examination of the red, scaly borders.
Majocchi's granuloma is seen as multiple follicular pustules on the skin, with involvement of one or both legs. It is often misdiagnosed as bacterial folliculitis and occurs in immunodeficient children in whom dermatophytes invade the follicular channels.
Tinea
pedis, onychomycosis
Tinea pedis is usually seen in adolescent males and involves the instep. Blisters are often present.
Classic adult tinea pedis is rarely seen in children, Weston said. This is the "moccasin" distribution—toe web plus toenail involvement.
This pattern represents long-standing tinea pedis and occasionally can occur in children whose father or older brothers have chronic, untreated athlete's foot," he said.
The responsible organisms for childhood tinea pedis include Trichophyton rubrum and Trichophyton mentagrophytes.
Onychomycosis is unusual in children. When it occurs, often just one or two nails are involved, which thicken and turn yellow.
"If many nails are involved, it is more likely psoriasis, lichen planus, or "20 nail dystrophy. The differential diagnosis is made by fungal culture of nail clippings; KOH examination is rarely positive," he said.
Management made easy
Griseofulvin is the treatment of choice for dermatophyte infections that involve hair or nails, Weston believes. He prescribes dosages of 20 mg/kg/day. "All the currently available topical antifungals work well in tinea corporis. Terbenafine looks like a promising new antifungal agent because it is fungicidal in low concentrations. It appears to work best in tinea pedis, tinea corporis, and onychomycosis as a 1% cream preparation," he said.
Presented at the Fifth Annual Masters of Pediatrics meeting, Miami Beach, Fla., Jan. 25-29, 1996