Acquired C1 esterase inhibitor deficiency
Acquired C1 esterase inhibitor deficiency, also referred to as acquired angioedema (AAE), is a rare medical condition that presents as body swelling that can be life-threatening and manifests due to another underlying medical condition.: 153 The acquired form of this disease can occur from a deficiency or abnormal function of the enzyme C1 esterase inhibitor (C1-INH). This disease is also abbreviated in medical literature as C1INH-AAE. This form of angioedema is considered acquired due to its association with lymphatic malignancies, immune system disorders, or infections. Typically, acquired angioedema presents later in adulthood, in contrast to hereditary angioedema which usually presents from early childhood and with similar symptoms.
| Acquired C1 esterase inhibitor deficiency | |
|---|---|
| Other names | Acquired angioedema |
| Angioedema (or swelling) of the face and upper lip | |
| Specialty | Hematology |
| Symptoms | Swelling |
| Complications | Airway obstruction, anaphylaxis |
| Usual onset | 4th decade of life and older |
| Duration | Episodic, typically lasting 2-4 days |
| Types | AAE-I, AAE-II, medication-induced AAE, estrogen-dependent AAE |
| Causes | Lymphatic malignancies, MGUS, autoimmune disorders |
| Diagnostic method | Medical examination, complement studies |
| Differential diagnosis | Hereditary angioedema, allergic reaction |
| Treatment | C1-INH concentrate |
| Prognosis | Dependent on resolution of underlying disorder |
| Frequency | 1:10,000 - 1:150,000 |
Acquired angioedema is usually found after recurrent episodes of swelling and can in some cases take several months to diagnose. Diagnosis usually consists of medical evaluation in addition to laboratory testing. Laboratory evaluation includes complement studies, in which typical cases demonstrate low C4 levels, low C1q levels, and normal C3 levels. Determining the etiology, or cause, of acquired angioedema is often helpful in providing appropriate management of AAE.
Management of AAE usually includes treating any underlying disorder that could be responsible for the condition. Additionally, symptom management is important, especially in cases that are life-threatening. There are medications available to treat AAE, which are focused on replacing deficient levels of C1-INH or abnormal C1-INH enzymes. There are some cases of partial improvement and full resolution with treatment of the underlying medical problems contributing to AAE.