A 21-year-old woman presented to urgent care with a fever and worsening facial rash that both began 2 days prior.

The rash started as a small red spot on her right cheek. She was prescribed trimethoprim-sulfamethoxazole. One day later, she went to the emergency department with no improvement. She was given a dose of intravenous ceftriaxone and discharged with a prescription for oral cephalexin. The next day, the rash had become more extensive and tender.

The patient had no recent travel, contact with people who were sick, or trauma to the area. She had no other significant symptoms. Her vital signs were normal, and she was afebrile.

Physical examination revealed a large erythematous area on her right cheek that was tender but not fluctuant (Figure 1). Her right upper eyelid was swollen, but she had no pain with eye movements. Her oral cavity was normal with no visible lesions. Computed tomography did not show an abscess or abnormality of the orofacial tissues or retropharyngeal space.

QUESTION

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