A curious case of facial swelling in the night-time

A 57 year old woman presented to the emergency department with swelling of the lips and oropharynx of one hour’s duration. Treatment for anaphylaxis was started but 30 minutes later she was much worse. After intubation, she was taken to the intensive care unit for airway management. She had attended the emergency department with similar symptoms one month earlier and had been treated with chlorphenamine and discharged home with an EpiPen. A referral to the allergy clinic was made. Her medical history included hypertension, although she had never received an angiotensin converting enzyme inhibitor. In addition, two years earlier she had been diagnosed with a B lymphoproliferative disorder, which was asymptomatic and under surveillance. She had no history of asthma but had reported facial swelling as a child after a bee sting. She had no known allergies, no family history of note, and took no regular drugs. Blood tests showed haemoglobin 91 g/L (reference range 130-180), mean cell volume 78.4 fL(80-98), platelets 159×109/L (150-400), total white cell count 21.9×109/L(4.0-11.0), lymphocytes 8.5×109/L (1.0-4.0), and tryptase 1.45 µg/L (0-11.4). A complement screen showed C1q 49 mg/L (50-250), C2 2.0 mg/L (14-25), C3 0.8 g/L (0.88-2.01), C4 <0.03 g/L (0.16-0.47), and C1 esterase inhibitor 54 mg/L (220-390). ### 1. How would you interpret the blood results? #### Answer The low C2, C4, and C1q values are indicative of complement C1 esterase inhibitor deficiency. She also had microcytic anaemia. #### Discussion Complement is a major component of innate immunity. It mediates various pathways involved in the immune response, including the classical, alternative, and lectin pathways, which are activated in various inflammatory or infective processes. C1-C4 are components of the classical pathway and are often low when …