Idiopatic angioedema treated with dapsone

The most commonly identified causes of angioedema are medications, allergens and physical agents, but most cases of angioedema are idiopathic. Treatment depends on identification of the causative agent and, especially when the mechanism is not identified, on the clinicians knowledge and experience with innovative therapeutic regimens.

A 48-year-old man presented with a 3-month history of recurrent severe episodes of angioedema affecting the lips, tongue and throat. A fiberoptic examination revealed laryngeal edema during some episodes. He did not report abdominal pain, nausea or vomiting. No precipitating factors were identified. The patient was not receiving angiotensin-converting enzyme inhibitors. For the previous 4 years, the patient had been receiving levothyroxine for autoimmune thyroiditis. There was no history of facial palsy or hereditary angioedema.

Skin prick test with aeroallergens, food, latex, Anisakis and patch test to a standard series (true test) were negative. Laboratory investigations revealed normal complete blood count (CBC), erythrocyte sedimentation rate, urinalysis, blood biochemistry, serum protein electrophoresis and serum immunoglobulins. IgE concentration was 30 UI/ml. Antiperoxidase antibodies were positive (535 UI/ml). Antinuclear antibodies serum immune complexes and rheumatoid factor were negative. Complement study during acute and asymptomatic periods revealed normal values of C1 esterase inhibitor, C1q, C3, C4, functional activity of C1 inhibitor and CH50. No pathologic findings were observed in a lip biopsy. The patient was treated with sedating and nonsedating H1 antihistamines and corticosteroids (prednisone 30 mg/day for 3 months) with no clinical improvement and treatment with 50 mg of dapsone daily was started. Glucose 6 phosphate dehydrogenase deficiency had previously been ruled out. The patient improved and antihistamine and corticoid treatment was withdrawn 1 month after starting the dapsone regimen. No episodes of angioedema appeared during the subsequent year. No reductions in hematologic parameters or adverse events were detected. Dapsone may be an alternative drug in extreme cases of idiopathic angioedema in patients with poor response to conventional therapy.