Non-myeloablative allogeneic stem cell transplantation: a new treatment option for acquired angioedema?

Introduction: Acquired angioedema is a rare disorder causing recurrent life-threatening angioedema, due to decreased activity of C1 esterase inhibitor.
Case Report: A 57-year-old man presented to our hospital with recurrent swelling of the hands, lips, tongue, scrotum and throat. Lab examination showed the presence of an IgM kappa monoclonal antibody. Additional analysis showed that in the IgM fraction autoantibody activity against C1 esterase inhibitor was present. This confirmed the diagnosis of acquired angioedema in the presence of lymphoplasmacytic lymphoma. Despite standard therapy, there was an increase in the episodes of laryngeal oedema. Therefore it was decided to perform a non-myeloablative allogeneic haematopoietic stem cell transplantation, with his HLA-identical brother as donor. The post-transplantation course was without complications. Five years following alloSCT he is in complete remission without symptoms and with increased C1 esterase inhibitor activity.
Discussion: In this case all other known treatment options for severe acquired angioedema failed. This is the first case describing treatment of severe acquired angioedema, caused by lymphoplasmacytic lymphoma, with an alloSCT.