Acquired angioedema associated with hereditary angioedema due to C1 inhibitor deficiency.

Angioedema caused by C1 inhibitor deficiency is a rare disorder that may be either hereditary or acquired, the latter being mainly associated with lymphoproliferative disorders. A 51-year-old woman who had suffered from episodes of acute peripheral edema since she was 12 was diagnosed with hereditary angioedema at the age of 40 and remained stable with stanozolol. Due to a worsening of her symptoms she was reassessed and low levels of C1q and an abnormal lymphocyte count were detected. Immunophenotyping of peripheral blood revealed 9% monoclonal lambda B cells with a follicular center phenotype. The histopathology was consistent with a grade II follicular lymphoma stage IV-A.With chemotherapy, the hematologic disease was controlled and C1q levels returned to normal values. This represents a rare case of a patient with hereditary angioedema who developed acquired angioedema due to a lymphoma that was associated with a reduction in the levels of C1q as her symptoms worsened.