Erythema Nodosum Associated with Kerion: A Case Series and Narrative Review of the Literature

Kerion is a form of inflammatory tinea capitis, a fungal infection caused by various zoophilic, geophilic, and anthropophilic pathogens. Erythema nodosum (EN), a form of septal panniculitis, can be considered a dermatophyte id reaction that occurs outside the primary site of dermatophyte infection. The association between EN and kerion is rarely reported, with most cases following Trichophyton mentagrophytes scalp infections. Here, we describe three cases of EN associated with kerion caused by T. mentagrophytes, successfully treated with itraconazole or griseofulvin plus prednisone. Additionally, we conducted a narrative review of the literature, identifying 23 reported cases of EN associated with kerion on PubMed. The most commonly reported fungus was T. mentagrophytes (78.25%). In 52.17% of cases, patients developed EN after initiating antifungal treatment, with a mean onset time of 11.58 days (SD 7.3). Griseofulvin remains a mainstay treatment. The mean time for EN resolution was 8.31 days (SD 4.15), and the median duration of treatment for kerion leading to a complete response was 6 weeks (IQR 6–8). Scarring alopecia is a common sequela following kerion, and the use of corticosteroids has been recommended as adjunct therapy to minimize the risk of scarring.