Rituximab in the Treatment of Acquired Angioedema Secondary to Marginal Zone Lymphoma of the Spleen.

Angioedema occurs in less than 1-2% of the population and amongst these cases, those with acquired angioedema are less prevalent than hereditary angioedema. Amongst cases of acquired angioedema, studies have shown that they were highly linked with an associated lymphoproliferative disorder, suspected secondary to the production of neutralizing autoantibodies from pathological B cell proliferation. We present a case of a patient who presented with recurrent episodes of angioedema and was found to have low C4 and C1 esterase function, initially concerning for a hereditary angioedema variant, who was subsequently found to have marginal B cell lymphoma mimicking hereditary angioedema.