This asymptomatic plaque on the left cheek of a 12-year-old girl was not respondingto a cream that her physician had prescribed when the rash began.
Case 1:This asymptomatic plaque on the left cheek of a 12-year-old girl was not respondingto a cream that her physician had prescribed when the rash began.Is there a simple diagnostic test? Is there an effective topical therapy?
Case 1: Tinea faciei is a dermatophyte infection of the face that, in myexperience, most often presents in childhood as misdiagnosed eczemathat does not respond to topical corticosteroid therapy. As in eczema, theeruption is papulosquamous; however, the morphology and the failure torespond to topical steroids are the key elements in the diagnosis of thispresentation.
The morphologic features to look for are the active inflammatoryborder and the tendency to central clearing that results in annular and polycyclicconfigurations of the plaques.The borders are not only scaly, butoften papulovesicular with crusting.Also, if the follicular involvement isprominent, the lesions may look"granulomatous." The lesions appearin small numbers and are unilateralin almost all presentations.
The most useful diagnostic testis the potassium hydroxide (KOH)preparation, which can be performedas an office procedure or inyour local laboratory. Take a scrapingfrom the inside edge of the advancingborder or--if a blister ispresent--from the underside of ablister roof.
I treat patients based on theKOH results because cultures ofdermatophytes may not be availablefor weeks--a period during whichmost patients can be cured. Thedermatophytes implicated in this infectionare commonly zoophilic:direct skin contact with pets is themost common source of infectionamong affected patients in my practice.I can always imagine the gerbil,kitten, or puppy snuggling up tothe cheeks of the infected child.Zoophilic dermatophytes producethe most inflammatory skin reactionsbut, on occasion, they will resolvespontaneously. The specificdermatophyte is often based on the regional prevalence of the dermatophytesthemselves.
I attempt to treat these infections topically with an antifungal cream.More often than not, however, there is significant follicular involvement thatrequires systemic antifungal therapy. If 3 weeks of topical therapy with eitherciclopirox or terbinafine does not eradicate the infection, I add systemictherapy with terbinafine tablets for 4 weeks.
I also recommend questioning other members of the patient's familyabout scaly or itchy skin lesions that may have developed over the precedingweeks. One infected pet can affect an entire family.
Case 2:These 2 adolescents have a skin infection with the same organism. Their presentations are,however, unique. The varied colors explain the name of this condition.How do you decide whether systemic therapy will be indicated? Also, what advice will yougive the patients about the chance of recurrent infection?
Case 2: Tinea versicolor, the "many colored fungus,"is a superficial skin infection with the yeast Malasseziafurfur. The infection most commonly affects personswho live or visit warm, moist climates. In southern climates,up to half the population may be affected. In mynorthern climate, I often see this infection in patientswho have returned from a winter vacation in a warm localeor who use tanning beds. Tanning in these bedsrequires the use of shared equipment: the heat andsweat produced during light exposure is the perfect environmentfor the transfer of the organism.
Tinea versicolor presents as slightly pruritic orasymptomatic scaling patches that coalesce to involvelarge areas of the skin surface of the trunk and extremities--particularly the upper arms and chest. A characteristicfeatureis the presenceof smaller roundlesions at theperiphery of thelarger patches,which you wouldpredict to occurin a superficialskin infection.
The term"versicolor" derivesfrom thefact that thepatches vary from red to brown to white. Affected personstend to have "one-color" infections.
The diagnosis is confirmed by KOH examination,which shows multiple short hyphae and round yeastforms ("spaghetti and meatballs").
White patches can be clearly distinguished fromvitiligo and post-inflammatory hypopigmentation if finesuperficial scales are present when the patches are lightlyscratched.
Persons probably carry M furfur as dictated bygenetic susceptibility: infection develops when local environmentalconditions (heat, humidity, change in skinsurface lipids, or altered immunity) favor the developmentof the hyphal form of the yeast. The organism producesazaelic acid that inhibits normal pigment production:the result is hypopigmentation.
The treatment of tinea versicolor depends on theextent of the infection and patient preferences for topicalversus systemic therapy. Topical therapy for extensiveinfection may be accomplished by the application of seleniumsulfide (2.5%) or ketoconazole (2%) shampoos for1 week. The shampoo is applied for 15 minutes eachday and then showered off. Topical imidazole creamsapplied twice daily for 2 weeks will clear localized areas.
There are also many preparationsthat remove the stratumcorneum that have proved effective.These include propylene glycoland salicylic acid (I refer you tothe texts for the exact formulas).Systemic therapy with itraconazole(2.5 mg/kg/d for 7 days) is my favoriteoption whenever the involvementis extensive or multiply recurrent,when topical agents havefailed, and when general medicalconditions allow.
It is crucial to counsel patientsthat the condition is likely to recur, that it may takemonths for repigmentation to occur, and that applicationsof medicine beyond the prescribed duration willonly irritate the skin. I advise patients that they can considerre-treatment when they scratch the white patchesand this brings up a fine scale that does not develop inthe adjacent normal skin.