Atypical Microsporum canis variant in an immunosuppressed child

A 10-year old boy with X-chromosomal adrenoleukodystrophy presented with scaly patches on the scalp and diffuse effluvium. He was on immunosuppressive therapy because of a chronic graft-versus-host-reaction after allogenic bone marrow transplantation. At home he had been in contact with cats, rabbits and guinea pigs. Through Wood light and KOH examination, we confirmed the diagnosis of tinea capitis and started antimycotic therapy. The morphology of the culture first suggested Epidermophyton floccosum, Trichophyton mentagrophytes var. nodulare or Trichophyton tonsurans as possible causes for this infection. Further studies, however, revealed an atypical form of Microsporum canis infection.