[Tinea barbae profunda by Arthroderma benhamiae. A diagnostic challenge]

Dermatomycoses due to pets and farm animals are often a clinical and diagnostic challenge for dermatologists. A 24-year-old man presented with inflammatory skin changes on his cheeks and chin. Because of negative fungal culture and the clinical appearance of a highly inflammatory process, our first diagnosis was a bacterial pyoderma. Polymerase chain reaction (PCR) identified Arthroderma benhamiae in both the patient and his guinea pig. A. benhamiae is a zoophilic dermatophyte which belongs to the Trichophyton mentagrophytes-complex. The fungus is acquired from guinea pigs and causes highly inflammatory forms of tinea. PCR-based diagnostics are quick and simple tools to identify this pathogen, so that suitable antimycotic therapy can be initiated quickly.