[The course of acquired C 1 esterase inhibitor deficiency in lymphoproliferative syndrome].

Acquired deficiency in C1 esterase inhibitor (C1 INH) was first described by Caldwell in 1972. Since that date, about 30 cases have been reported, in most cases during proliferative lymphocyte B syndromes. The acquired C1 INH deficiency can provoke episodes of angioneurotic edema as in hereditary AE. The complement profile differs, notably by the usual sudden fall in C1. Documented data suggest consumption of complement and therefore of C1 INH. The present case is the first reported of an acquired C1 INH deficiency during a cold hemagglutinin disease. The activation of complement by the classical pathway appears provoked by tumoral cells rather than a humoral factor, as suggested by the efficacy of anti-tumoral therapy in contrast to plasmapheresis in the present case. A possible mechanism for the C1 INH deficiency is discussed.