Hereditary angioedema.

A 14-year-old African American female presented to the emergency department with spontaneous, sudden-onset lip swelling for 1 h. On examination, there was significant water-bag edema of the upper lip extending to the philtrum and premaxilla. Nasopharyngeal laryngoscopy revealed a patent airway without edema. She was initiated on intravenous dexamethasone, famotidine, and diphenhydramine, after which her edema improved but did not resolve. She was subsequently transferred to a local pediatric hospital and upon further testing she was found to have a C1 esterase inhibitor de novo gene mutation. Angioedema causes localized, non-pitting edema of the dermis, subcutaneous and submucosal tissue, and often manifests in the lips, face, mouth, and throat. Signs of laryngeal involvement include change in voice, stridor, dysphagia, and dyspnea. When laryngeal edema is present, it may necessitate definitive airway management and patients should be monitored in the intensive care unit.