Angioedema presenting as chronic gastrointestinal symptoms

Gastrointestinal complaints may be the presenting feature of patients with acquired or hereditary angioedema. We describe two patients with episodic nausea, abdominal pain, and cramping secondary to C1 inhibitor deficiency. In one patient, an acquired deficiency arose as a paraneoplastic syndrome with abdominal complaints preceding the diagnosis of an occult lymphoma. The second patient presented at age 61 with abdominal complaints secondary to a hereditary deficiency of C1 inhibitor. The patients' symptoms were due to gastrointestinal angioedema, resulting from episodic unregulated complement activation. The biochemical mechanism of this unusual syndrome and its diagnostic importance are discussed. A C1 inhibitor deficiency should be considered in patients with unexplained abdominal symptoms suggestive of intestinal pseudo-obstruction.