A 12-year-old girl is brought to the office due to a 2-hour history of upper and lower extremity swelling. There is no redness, itching, or pain. She has had similar symptoms along with abdominal pain following minor injuries and injections in the past. These episodes usually last for 2 to 4 days and resolve spontaneously. The patient has no history of severe or frequent infections. Her father has had similar episodes but was never evaluated. Temperature is 37 C (98.6 F), blood pressure is 110/78 mm Hg, pulse is 88/min, and respirations are 16/min. Oxygen saturation is 98% on room air. Examination shows nonpitting edema extending from hands to elbows and from feet to knees in an asymmetrical fashion. Cardiopulmonary examination is normal. Which of the following is the most appropriate next step in evaluation?

Question

A 12-year-old girl is brought to the office due to a 2-hour history of upper and lower extremity swelling.  There is no redness, itching, or pain.  She has had similar symptoms along with abdominal pain following minor injuries and injections in the past.  These episodes usually last for 2 to 4 days and resolve spontaneously.  The patient has no history of severe or frequent infections.  Her father has had similar episodes but was never evaluated.  Temperature is 37 C (98.6 F), blood pressure is 110/78 mm Hg, pulse is 88/min, and respirations are 16/min.  Oxygen saturation is 98% on room air.  Examination shows nonpitting edema extending from hands to elbows and from feet to knees in an asymmetrical fashion.  Cardiopulmonary examination is normal.  Which of the following is the most appropriate next step in evaluation?

Quizplus · Accepted Answer

11ec25c8_d620_98c7_bc81_67c5055a8327_MD0003_00 This patient's episodic swelling is most likely caused by excessive bradykinin due to hereditary angioedema. This condition is typically caused by an autosomal dominant mutation leading to deficiency or dysfunction of C1 inhibitor (previously referred to as C1 esterase inhibitor), which normally downregulates bradykinin production. C1 inhibitor Hereditary angioedema should be suspected in a patient with a family history of angioedema and recurrent episodes of nonpitting edema in the absence of pruritus or urticaria. The face, limbs, or genitalia are most commonly affected, and distribution is typically asymmetric. Mucosal involvement can lead to episodic, colicky abdominal pain from bowel wall edema and life-threatening airway obstruction from laryngeal edema. These organ systems can be affected in isolation or associated with cutaneous swelling. Attacks are often precipitated by stress or minor trauma (eg, injections), as seen in this child. Diagnosis of hereditary angioedema is supported by complement testing showing low C4 levels, which are caused by exaggerated cleavage of C4 by uninhibited C1 complex. Low levels of C1 inhibitor protein or C1 inhibitor function confirm the diagnosis. cleavage of C4 (Choice A) Antinuclear antibodies evaluate for autoimmune disorders such as systemic lupus erythematosus and juvenile idiopathic arthritis. Joint swelling can occur but not cutaneous edema. (Choices C, D, and E) Serum IgE and skin patch testing may be performed to identify the trigger for an allergic reaction, which can cause angioedema mediated by histamine release from mast cells. Similarly, selective IgA deficiency increases risk of anaphylaxis (although only with blood product exposure), which can present with angioedema. In either case, other histamine-mediated manifestations would be expected (eg, pruritus, urticaria, bronchospasm, hypotension). Absence of these features is suggestive of bradykinin-mediated angioedema, making IgE, IgA, and patch testing unnecessary. Educational objective: Hereditary angioedema (C1 inhibitor deficiency) should be suspected in a patient with recurrent episodes of edema (eg, face, limbs, bowel, larynx), particularly with a positive family history. Low C4 on complement testing is consistent with the diagnosis. References: Hereditary and acquired angioedema. (http://www.ncbi.nlm.nih.gov/pubmed/31690390)

A 12-Year-Old Girl Is Brought to the Office Due to a 2-Hour