[Erythema nodosum due to tinea]

Area of Science:

• Dermatology
• Infectious Diseases
• Pathology

Background:

• Erythema nodosum (EN) is the most common panniculitis variant.
• A kerion is a severe, suppurative fungal infection of the scalp.
• EN can manifest as a hypersensitivity reaction to various triggers.

Observation:

• A 9-year-old presented with a 15-day history of a vertex scalp plaque that became painful and purulent.
• The child developed symmetrical, painful, erythematous nodules on the legs and forearms.
• Scalp lesion cultures confirmed *Trichophyton mentagrophytes*; skin biopsy confirmed EN.

Findings:

• The patient was diagnosed with erythema nodosum secondary to a scalp kerion.
• No other underlying medical conditions or infections were identified.
• Treatment involved oral and topical antifungals, rest, and limb elevation.

Implications:

• This case underscores the rare but possible association between scalp kerion and erythema nodosum.
• It suggests EN can precede antifungal therapy for tinea capitis.
• Successful treatment of the fungal infection led to spontaneous resolution of EN symptoms.