A 39-year-old woman, 8 weeks postpartum and breastfeeding her infant, presented with an eruption on the right side of her face and into her hairline for the past month. She was given acyclovir, valacyclovir, and prednisone by her obstetrician without any clinical improvement. On physical examination, she presented with an erythematous scaly plaque on the right side of her face (Fig. 1). She saw a dermatologist, who performed a potassium hydroxide (KOH) prep, which was negative. She was prescribed trimethoprim/sulfamethoxazole, clindamycin gel, desonide ointment, and doxycycline, and still no improvement was seen. A 4-mm punch biopsy was eventually performed, and a periodic acid–Schiff stain revealed hyphae in the stratum corneum.
Tinea faciei (TF) is a dermatophyte infection of the face. TF can present classically with scaly, raised annular lesions, or it can present atypically, making it easy to misdiagnose. The definitive diagnosis can usually be made by KOH examination and fungal cultures (Bolognia et al., 2018). As in our case, a false-negative KOH examination should not rule out TF if suspected clinically.