Introduction . Tinea faciei is quite a rare infection in the developed countries. Proper diagnosis of the causative pathogen is essential for successful treatment.

Objective . To present the case of an 11-year-old patient in whom wrong diagnosis and treatment led to complications and finally to face deformation.

Case report . A small inflammatory skin lesion appeared on the chin and extended quickly to form a deep infiltration. Despite surgical incision, drainage and broad-spectrum antibiotics, the skin lesion progressed to an ulceration of 2 × 3 cm in diameter with necrotic crust. In direct mycological smear hyphae were observed and in the culture Stenotrophomonas maltophilia was found. Systemic treatment with terbinafine and trimethoprim-sulfamethoxazole led to almost complete healing with a scar and chin deformation as a result.

Conclusions . In the differential diagnosis of skin lesions on the chin fungal infection should always be considered, confirmed or ruled out before starting the therapy.