'Fungal Fridays' and other tips for onychomycosis.
The presence of tinea pedis on the plantar surface or web space confirms that dinical suspicion. "There are several exceptions, one of which is someone who has obtained an infection from a pedicure," said Dr. Elewski, professor of dermatology at the University of Alabama, Birmingham.
"You can't eliminate that. So if you have a patient with pristine feet and they have no [previous] history of tinea pedis, ask if they get regular pedicures, because you can get a direct infection of the nail plate from a pedicure," she explained.
The other exceptions are white superficial onychomycosis and proximal white subungual onychomycosis, two subtypes in which the fungus directly attacks the nail plate rather than the skin first.
Dr. Elewski provided several other clinical pearls regarding onychomycosis:
* A patient with abnormal fingernails and normal toenails is unlikely to have onychomycosis. The exception is Candida onycholysis. "This occurs commonly in women who have Raynaud's syndrome and other patients who have collagen vascular disease, but that's a very small minority of patients," she said.
* Fluconazole 200-400 mg once a week is effective for Candida onychomycosis or paronychia. "We underuse this drug in dermatology," she said. "It is a good anti fungal and it's very cheap, about 25 cents per tablet. You only need to treat for 6-8 weeks in most patients."
She usually instructs her patients to take fluconazole on Fridays and uses the term "fungal Fridays" as a catchy reminder. Some of her dermatology residents prefer Tuesdays or, as they call it, "Toesdays."
* Know the bad prognostic factors of onychomycosis. These include dermatophytoma, thick nail, a total dystrophic nail, predominantly lateral nail involvement, and immunocompromised and/or diabetic patients.
Physicians can improve the prognosis in patients with dermatophytoma by debriding the area as much as possible. "You can give patients antifungal cream, lotion, or gel to smear under it, and then treat it with an oral antifungal," said Dr. Elewski, a past president of the American Academy of Dermatology.
She also noted that patients with thick nails require careful evaluation because not all of them will have onychomycosis. "Thick nails could come from trauma, from running or skiing, or from runner's toe," she explained.
In patients with lateral nail involvement, she clips away at the lateral edge, smears in antifungal cream and continues treatment with oral antifungals.
Most patients with a bad prognostic factor will require treatment with oral terbinafine 250 mg daily or itraconazole 400 mg daily for 1 week per month for 4 months or longer.
* Itraconazole is the choice in nondermatophyte mold infections of the nail.
There are two other drugs on the horizon "that may supersede itraconazole in this situation," Dr. Elewski said. These include posaconazole (Noxafil), which is not approved for this indication but is under investigation, and a drug in development called albaconazole.
Currently, itraconazole given in a pulse fashion is preferred. The recommended dose is 400 mg/day for 1 week per month. "I generally use it for 4 months or longer if it's a nondermatophyte mold," she said.
* Topical antimycotic agents may be sufficient to treat onychomycosis in certain situations. The only topical agent that is approved by the Food and Drug Administration for onychomycosis is 8% ciclopirox olamine lacquer. Dr. Elewski said that she also finds it useful in white superficial onychomycosis and in minimal nail disease.
* The nail can provide dues to skin disease. She discussed the case of a patient who presented with a scaly dermatosis on the pretibial area. "Is this eczema? Stasis dermatitis?" she asked. "If the toes are abnormal and the patient has onychomycosis, there is a high likelihood that a scaly rash on the lower legs could be a dermatophyte infection. If the toes are normal, the patient probably does not have a dermatophyte infection on the lower legs."
Diagnosis of onychomycosis is made by a microscopy with potassium hydroxide test (KOH), culture, and nail biopsy. Dr. Elewski warned, however, that culture can be the most variable of the three. "Even in the perfect situation you may not grow a dermatophyte, or you may grow a contaminant that is unrelated to the true infection that is in the nail," she said. "Think of your KOH nail biopsy as yielding about the same information. If KOH is positive, the diagnosis is made."
Dr. Elewski disclosed that she has conducted clinical research for Novartis, Barrier Therapeutics, and Stiefel Laboratories.
BY DOUG BRUNK
San Diego Bureau
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|Title Annotation:||Skin Disorders|
|Publication:||Family Practice News|
|Article Type:||Case study|
|Date:||Nov 1, 2007|
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