Can you identify this infection in its various guises?

Dermclinic
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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 you give the patients about the chance of recurrent infection?


(Answer on next page.)

Dermclini – Answer



Case 2: Tinea versicolor, the "many colored fungus," is a superficial skin infection with the yeast Malassezia furfur. The infection most commonly affects persons who live or visit warm, moist climates. In southern climates, up to half the population may be affected. In my northern climate, I often see this infection in patients who have returned from a winter vacation in a warm locale or who use tanning beds. Tanning in these beds requires the use of shared equipment: the heat and sweat produced during light exposure is the perfect environment for the transfer of the organism.

Tinea versicolor presents as slightly pruritic or asymptomatic scaling patches that coalesce to involve large areas of the skin surface of the trunk and extremities—particularly the upper arms and chest. A characteristic feature is the presence of smaller round lesions at the periphery of the larger patches, which you would predict to occur in a superficial skin infection.

The term "versicolor" derives from the fact that the patches vary from red to brown to white. Affected persons tend to have "one-color" infections.

The diagnosis is confirmed by KOH examination, which shows multiple short hyphae and round yeast forms ("spaghetti and meatballs").

White patches can be clearly distinguished from vitiligo and post-inflammatory hypopigmentation if fine superficial scales are present when the patches are lightly scratched.

Persons probably carry M furfur as dictated by genetic susceptibility: infection develops when local environmental conditions (heat, humidity, change in skin surface lipids, or altered immunity) favor the development of the hyphal form of the yeast. The organism produces azaelic acid that inhibits normal pigment production: the result is hypopigmentation.

The treatment of tinea versicolor depends on the extent of the infection and patient preferences for topical versus systemic therapy. Topical therapy for extensive infection may be accomplished by the application of selenium sulfide (2.5%) or ketoconazole (2%) shampoos for 1 week. The shampoo is applied for 15 minutes each day and then showered off. Topical imidazole creams applied twice daily for 2 weeks will clear localized areas.

There are also many preparations that remove the stratum corneum that have proved effective. These include propylene glycol and salicylic acid (I refer you to the texts for the exact formulas). Systemic therapy with itraconazole (2.5 mg/kg/d for 7 days) is my favorite option whenever the involvement is extensive or multiply recurrent, when topical agents have failed, and when general medical conditions allow.

It is crucial to counsel patients that the condition is likely to recur, that it may take months for repigmentation to occur, and that applications of medicine beyond the prescribed duration will only irritate the skin. I advise patients that they can consider re-treatment when they scratch the white patches and this brings up a fine scale that does not develop in the adjacent normal skin.