A healthy 8-year-old boy was observed in a Dermatology consultation, with a 4-week history of an erythematous patch on the scalp with alopecia measuring approximately 3 cm long axis. Scalp dermoscopy revealed broken hairs, black dots and pustules and the Wood´s lamp examination was negative. There were no local adenopathies. His past medical history was unremarkable. A recent contact with a cat was described. There was no history of fever or a recent travel.
A hair sample was obtained for mycological examination and he was started on an eight-week course of microsized griseofulvin (15 mg/kg/day orally) and ketoconazole shampoo. Approximately ten days after initiation of therapy, there was a clinical worsening, with transformation into an exudative swelling with purulent discharge, pain and occipital adenopathies (Figure 1). Additional collection of pus for bacteriologic examination was performed. He continued treatment with griseofulvin and was started on topical betamethasone plus gentamicin ointment and clarithromycin (15 mg/kg/day orally), which he completed for seven days. Because of persistent signs of inflammation, despite the negativity of the bacteriological examination, he was switched to amoxicillin plus clavulanic acid (90 mg/kg/day orally), which he continued for another seven days. The inflammation progressively improved, with complete resolution with residual alopecia (Figure 2). Seven weeks after diagnosis, the scalp scraping mycologic examination revealed
Trichophyton tonsurans.
Figure 1. Subcutaneous nodule with purulent discharge.
Figure 2. Progressive resolution of the lesion with residual alopecia.
What is the diagnosis?