Tinea capitis due to Microsporum gypseum

ARTICLE

Microsporum gypseum (M. gypseum) is a geophilic dermatophyte. The source of human infection has been traced to soil, dogs and cats [1]. While this fungus is still very rare as a source of human dermatophyte infections, the incidence of infection due to this organism has been gradually rising. The common practice of keeping dogs and cats as pets causes soil pollution and increases the risk that humans will contact infections. We report our experience with a two-year-old boy who developed tinea capitis due to M. gypseum at the site of a small wound.

Case report

A two-year-old Japanese boy living in Tokyo was referred to our department for evaluation of a solitary patch of hair loss and swelling of the lymph node behind his left ear. Some days before he had suffered a small cut on his head while playing in the park. He did not have any pets. Shortly afterwards, he visited his primary care physician with an inflamed plaque involving the left frontal area. Treatment with oral antibiotics (cefdinir) produced only a minimal response. On examination at our department, a 20 x 15 mm area of erythematous plaque with follicular pustules and crusting was observed on the front part of the scalp (Fig. 1). The lymph node behind his left ear was swelling. A potassium hydroxide preparation made from scrapings from the involved scalp and hairs yielded no diagnosis. A fungal culture of pustules and scales showed some growth in seven days. A mature colony plated on Sabouraud dextrose agar showed a powdery, cinnamon-colored surface and feathery indistinct edge with a pale color on the reverse side (Fig. 2). Slide-culture examination showed a fusiform macroconidia that was rather thin walled, made up of four or five cells with rounded extremities (Fig. 3). We diagnosed the lesion as tinea capitis due to M. gypseum. Treatment with griseofulvin 125 mg per day for 5 weeks was effective.

Discussion

M. gypseum is a rapidly growing, geophilic dermatophyte found in small mammals, such as cats and rodents [1]. As M.gypseum elicits a strong foreign body reaction, human dermatophyte infection due to M. gypseum produces heavy inflammation. Physicians sometimes mistake infections due to M. gypseum as eczema or bacterial infection. Most cases occur in children [2-5]. The most frequent clinical presentation of M. gypseum infection is tinea corporis [5, 6]. Infection in the scalp may occur with kerion formation. M. gypseum is a rare source of human dermatophyte infections in the world [2, 3, 5-8]. In Japan 271 cases have been seen in the last 50 years [6]. This infectious disease is apt to occur in big cities such as Tokyo. Human dermatophyte infection due to M. gypseum has increased in the last decade [9]. The common practice of keeping dogs and cats as pets causes soil contamination and increases the risk that humans will contract the infection [9].

Article accepted on 2/4/02

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