Acquired C1 esterase inhibitor deficiency

Acquired C1 esterase inhibitor deficiency

Angioedema of the face

Acquired C1 esterase inhibitor deficiency is a rare condition characterized by the deficiency of the C1 esterase inhibitor (C1-INH), which leads to episodes of angioedema. This condition is distinct from hereditary angioedema and is often associated with other underlying diseases.

Pathophysiology

The C1 esterase inhibitor is a crucial component of the complement system, which is part of the body's immune response. It regulates the activation of the complement pathway, particularly the classical pathway. In acquired C1 esterase inhibitor deficiency, the lack of functional C1-INH leads to uncontrolled activation of the complement system, resulting in excessive production of bradykinin, a peptide that increases vascular permeability and causes angioedema.

Complement activation

Causes

Acquired C1 esterase inhibitor deficiency is often associated with other medical conditions, such as lymphoproliferative disorders (e.g., non-Hodgkin lymphoma) and autoimmune diseases. It can also occur in the context of monoclonal gammopathy of undetermined significance (MGUS).

Clinical Presentation

Patients with acquired C1 esterase inhibitor deficiency typically present with recurrent episodes of angioedema, which can affect the face, extremities, gastrointestinal tract, and airways. Unlike allergic reactions, these episodes are not associated with urticaria or pruritus.

Angioedema affecting the face

Diagnosis

The diagnosis of acquired C1 esterase inhibitor deficiency involves measuring the levels and function of C1-INH in the blood. Low levels of C1-INH and C4, along with normal C1q levels, are indicative of the condition. A detailed patient history and examination are also crucial to rule out hereditary angioedema and identify any associated conditions.

Diagnostic approach to C1 inhibitor deficiency

Treatment

Management of acquired C1 esterase inhibitor deficiency focuses on treating the underlying condition and preventing angioedema attacks. Acute attacks can be treated with C1-INH replacement therapy, bradykinin receptor antagonists, or fresh frozen plasma. Long-term prophylaxis may involve the use of androgens or antifibrinolytics.

Prognosis

The prognosis of acquired C1 esterase inhibitor deficiency depends on the underlying condition. Effective management of the associated disease can lead to a reduction in the frequency and severity of angioedema attacks.

Related pages

• Hereditary angioedema
• Complement system
• Bradykinin
• Lymphoproliferative disorder

Gallery

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  Angioedema of the face

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  Complement activation

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  Angioedema affecting the face

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  Diagnostic approach to C1 inhibitor deficiency