A 40-year-old woman presented to the emergency department with a rash that began on her chest and spread to her extremities. She had a history of systemic onset juvenile idiopathic arthritis, chronic pain, and hypertension. Two weeks earlier, she was diagnosed with septic arthritis in her left knee that was treated with systemic ceftriaxone.

Physical examination showed a diffuse, pruritic, erythematous, maculopapular rash in a reticulated pattern (Figure 1). The patient responded well to high-dose oral steroids.

Question

Based on the patient's history and physical examination findings, which one of the following is the most likely diagnosis?

• A. Cutaneous manifestation of systemic onset juvenile idiopathic arthritis.

• B. Drug-induced hypersensitivity reaction.

• C. Small vessel vasculitis.

• D. Stevens-Johnson syndrome.

Discussion

The answer is B: drug-induced hypersensitivity reaction. This patient had a type IV hypersensitivity reaction, which appears four to 21 days after initiation of the causative medication. Although antibiotics are the most common inciting agents, nonsteroidal anti-inflammatory drugs, antiseizure medications, and chemotherapeutic agents have also been implicated. Risk factors include immunosuppression and viral infections in children.