Acquired C1 inhibitor deficiency revealing systemic lupus erythematosus.

We report the case of a previously healthy 54-year-old woman, without any family history, who developed an angioneurotic edema with acquired C1 inhibitor deficiency and systemic lupus erythematosus. The search for a lymphoproliferative disorder was negative. Hydroxychloroquine therapy induced simultaneous resolution of lupus and angioedema. The pathophysiology of this association is discussed.