Acquired C1 Inhibitor Deficiency in Lymphoma

Clinical Presentation

The primary symptoms of acquired C1 inhibitor deficiency in lymphoma are recurrent episodes of angioedema without urticaria, predominantly affecting the face, extremities, gastrointestinal tract, and upper airway, which can be life-threatening 1
Recurrent angioedema without urticaria is a key distinguishing feature, typically affecting middle-aged or older patients, unlike hereditary angioedema which presents in childhood 1
Patients with acquired C1 inhibitor deficiency often have no family history of angioedema and present with asymmetric, non-dependent, non-pruritic swelling 1
The American Academy of Allergy, Asthma, and Immunology recommends considering acquired C1 inhibitor deficiency in middle-aged or older patients with recurrent angioedema without urticaria 1

Laboratory findings include reduced C1 inhibitor function, low C4 levels, and low C1q levels, which distinguish it from hereditary angioedema 1
The World Allergy Organization suggests evaluating for underlying lymphoproliferative disorders in all patients diagnosed with acquired C1 inhibitor deficiency 1

The treatment approach differs from hereditary angioedema, with antifibrinolytic agents often being more effective than androgens 1
Successful treatment of lymphoma can lead to improvement or resolution of angioedema symptoms, highlighting the importance of addressing the underlying condition 1

The angioedema in these patients results from depletion of C1 inhibitor due to continuous activation of the classical complement pathway by lymphoma tissue, leading to uncontrolled activation of the contact system and excessive bradykinin production 1
The European Academy of Allergy and Clinical Immunology notes that the severity and frequency of angioedema attacks correlate with lymphoma activity, emphasizing the need for prompt diagnosis and treatment 1