Diagnosis, Course, and Management of Angioedema in Patients With Acquired C1-Inhibitor Deficiency

Angioedema Due to Acquired C1-Inhibitor Deficiency Without Hematological Condition: A Multicenter French Cohort Study of 34 Patients

BACKGROUND

Angioedema (AE) due to acquired C1-inhibitor deficiency (AAE-C1-INH) is a rare disease associating recurrent edema of the mucosa and skin. Several underlying diseases have been reported, mainly lymphoproliferative diseases and monoclonal gammopathy. However, 15% to 20% of patients never exhibit such a hematological condition.

OBJECTIVE

To analyze specific features of patients with AAE-C1-INH without a hematological condition.

METHODS

This is a multicenter, retrospective cohort study of patients with AAE-C1-INH without a hematological condition included from January 1999 to May 2024 in the French national CREAK (Centre de reference des angioedèmes à kinine) registry. The clinical and biological characteristics of patients were detailed and then compared with those of patients with AAE-C1-INH associated with lymphoid hemopathies or monoclonal gammopathy.

RESULTS

Thirty-four patients were included. All patients displayed a functional C1-INH below 50% of the reference value, 26 (76%) also had a decreased C1-INH antigen level, and 26 (76%) displayed anti-C1-INH antibodies. After a median follow-up of 65 months, 4 (12%) patients were in spontaneous complete remission of AE; 15 (44%) were in complete response under long-term prophylactic treatment. Compared with 75 patients with lymphoma-associated AAE-C1-INH, patients with AAE-C1-INH without a hematological condition displayed a higher incidence of anti-C1-INH antibodies and received more frequently symptomatic or prophylactic treatment with a lower remission rate at last follow-up. Clinical and biological features of patients with AAE-C1-INH without a hematological condition were similar to those of 30 patients with monoclonal gammopathy-associated AAE-C1-INH.

CONCLUSIONS

AAE-C1-INH without a hematological condition displays a different clinical and biological presentation from lymphoma-associated AAE-C1-INH. No autoimmune disease was identified. Unlike rituximab, long-term prophylaxis seems to prevent AE attacks among these patients.

Angioedema due to Acquired C1-Inhibitor Deficiency Associated With Monoclonal Gammopathies of Undetermined Significance Characteristics of a French National Cohort

BACKGROUND

No specific description of monoclonal gammopathies of undetermined significance (MGUS)-associated angioedema due to acquired C1 inhibitor deficiency (AAE-C1-INH) has been reported yet.

OBJECTIVE

To describe the biological and clinical characteristics, evolution, and response to treatment of MGUS-associated AAE-C1-INH.

MATERIALS AND METHODS

We conducted a French national retrospective observational study on MGUS-associated acquired angioedema spanning a 30-year period.

RESULTS

Forty-one patients with MGUS-associated AAE-C1-INH at diagnosis were included; 68% displayed anti-C1-INH antibodies. The monoclonal component was an IgM in 24 patients, IgG in 11, and IgA in 6 patients. The mean age at first angioedema attack was 63 years (standard deviation [SD] = 13 years) and at diagnosis 66 years (SD = 11 years). A total of 88% patients benefited from acute attack treatments, and 77% from long-term prophylaxis, either danazol, tranexamic acid, or lanadelumab. Median follow-up was 7 years, during which 14 patients (33%) evolved into well-defined malignant hemopathies. Fifty percent of patients were given a hematological treatment, either rituximab alone, indicated by recurrent attacks of angioedema in patients with AAE-C1-INH with anti-C1-INH antibodies, or validated combinations of chemotherapies, indicated by evolution into a lymphoma in 7 patients and a myeloma in 3 patients. Fifteen patients (35%) were in clinical complete remission of angioedema at last visit, of whom 60% had an undetectable serum monoclonal immunoglobulin.

CONCLUSIONS

Complete remission of AAE-C1-INH is correlated to complete remission of the underlying hematological malignancy, as defined by an undetectable serum monoclonal immunoglobulin. In our MGUS-associated acquired angioedema cohort, we recorded an incidence of evolution into hematological malignancy of 4% per patient-year. It is therefore crucial to conduct full hematological workup during follow-up at an annual rate, and earlier if AAE relapses or if acute attack frequency increases.

Acute Abdominal Pain as the Initial Presentation of an Acquired C1 Inhibitor Deficiency

Introduction

Acquired angioedema (AAE), a rare cause of adult-onset non-urticarial mucocutaneous angioedema, can present as acute abdomen, a frequent complaint in the emergency room (ER), often leading to unnecessary and potentially harmful procedures.

Case Presentation

We report a 47-year-old hypertense male, controlled with an angiotensin converting enzyme inhibitor (ACEI), who presented in the ER with progressively worsening abdominal pain, nausea, and vomiting, and a radiologic workup revealing small intestine thickening, initially diagnosed with ACEI-induced angioedema. However, further investigation revealed low serum levels of C4, C1q, and C1 inhibitors, with an abnormal function of the latter, favoring the diagnosis of AAE instead. The frequent association of this condition with lymphoproliferative disorders encouraged further studies, which unveiled a monoclonal gammopathy IgM/Kappa, representing an increased risk of Waldenström macroglobulinemia, non-Hodgkin lymphoma, and multiple myeloma.

Discussion

AAE should be regarded as an important differential diagnosis in patients presenting with acute abdomen in the ER, especially when more common causes are excluded. A correct and early diagnosis may represent a chance for a better prognosis of underlying diseases.

Classification, Diagnosis, and Pathology of Angioedema Without Hives

A clear disease classification schema coupled with an understanding of the specific mechanisms involved in the different types of angioedema without hives informs the diagnostic assessment. The recommended approach involves several key steps. Foremost is the recognizing of the clinical clues which allow for the differentiation of mast cell-mediated disorders from bradykinin-mediated angioedema. Enhanced vascular permeability related to bradykinin is of critical importance to identify given the implications for disease morbidity and risk of mortality. The ability to efficiently categorize and diagnose all forms of angioedema results in improved patient outcomes.

Deucrictibant for angioedema due to acquired C1-inhibitor deficiency: A randomized-controlled trial

BACKGROUND

Angioedema due to acquired C1-inhibitor deficiency is a very rare but serious disease, with an estimated prevalence of 1 per 500,000 persons. There are no approved therapies to treat or prevent angioedema swelling in patients with this condition. Deucrictibant is a specific, orally bioavailable, competitive antagonist of the bradykinin B2 receptor currently under investigation for hereditary angioedema.

OBJECTIVE

Our aim was to assess the efficacy and safety of deucrictibant as acute and prophylactic treatment for angioedema due to acquired C1-inhibitor deficiency.

METHODS

A 2-part, randomized, double-blind, placebo-controlled crossover study was conducted. In Part 1, 4 consecutive angioedema attacks were treated with 3 doses of deucrictibant (10 mg, 20 mg, and 30 mg) or placebo. In Part 2, deucricibant, 20 mg, or placebo was administered twice daily for 2 treatment periods of 8 weeks.

RESULTS

Three patients were enrolled; of those 3 patients, 1 completed both study parts and 2 completed only Part 2. In Part 1, a reduction in attack severity was observed in the 3 attacks treated with deucrictibant as opposed to an increase in severity of the attack treated with placebo. In Part 2, the individual mean monthly attack rates were 2.0, 0.6, and 1.0 during the placebo period and 0.0 across all patients during treatment with deucrictibant. There were no severe adverse events and 1 self-limiting treatment-emergent adverse event (abdominal pain).

CONCLUSIONS

Deucrictibant has the potential to effectively and safely treat and prevent angioedema attacks due to acquired C1-inhibitor deficiency.

The real life experience goes on: update after 4 years on the first cohort treated with lanadelumab at our center

Introduction

Lanadelumab is a first-line long-term prophylaxis (LTP) in hereditary angioedema (HAE). Real-life data on its long-term efficacy and safety are limited. It is unknown whether patients using lanadelumab need short-term prophylaxis (STP).

Objectives

To provide 4-year follow-up data for our first 34 patients treating with lanadelumab.

Methods

Patients were assessed for their current injection interval, attacks, treatment satisfaction, disease control (AECT), quality of life impairment (AE-QoL), events that can induce attacks, and the use of STP since the start of their treatment with lanadelumab.

Results

Of 34 patients who started lanadelumab treatment, 32 were still using it after 4 years, with a median injection interval of 33 (range 14-90) days. HAE patients (n=28) reported longer intervals, i.e. 35 (14-90) days, than patients with angioedema due to acquired C1 inhibitor deficiency (n=4, 23 (14-31) days). With their current injection intervals, used for a mean duration of 29 ± 17 months, patients reported a yearly attack rate of 0.3 ± 0.1. More than 70% of patients were attack-free since starting their current injection interval. All patients reported well-controlled disease, i.e. ≥10 points in the AECT; 21 patients had complete control (16 points). AE-QoL scores improved further compared to our initial report, most prominently in the fears/shame domain (-6 points). Treatment satisfaction was very high. No angioedema occurred after 146 of 147 potentially attack-inducing medical procedures without STP.

Conclusions

Our results demonstrate the long-term efficacy and safety of lanadelumab in real-life and question the need for STP in patients who use effective LTP.

Efficacy and Safety of Rituximab-Based Treatments in Angioedema With Acquired C1-Inhibitor Deficiency

BACKGROUND

Angioedema (AE) due to acquired C1-inhibitor (C1-INH) deficiency (AAE-C1-INH) is related to excessive consumption of C1-INH or to anti-C1-INH antibodies, and is frequently associated with lymphoproliferative syndromes or monoclonal gammopathies. Standard of care for prophylactic treatment in this condition is not established. Rituximab may be effective to prevent attacks, especially if the lymphoid hemopathy is controlled, but data are scarce.

OBJECTIVE

To evaluate efficacy of rituximab in AAE-C1-INH.

METHODS

A retrospective multicenter study was carried out in France, including patients with AAE-C1-INH treated with rituximab between April 2005 and July 2019.

RESULTS

Fifty-five patients with AAE-C1-INH were included in the study, and 23 of them had an anti-C1-INH antibody. A lymphoid malignancy was identified in 39 patients, and a monoclonal gammopathy in 9. There was no associated condition in 7 cases. Thirty patients received rituximab alone or in association with chemotherapy (n = 25). Among 51 patients with available follow-up, 34 patients were in clinical remission and 17 patients had active AE after a median follow-up of 3.9 years (interquartile range, 1.5-7.7). Three patients died. The presence of anti-C1-INH antibodies was associated with a lower probability of AE remission (hazard ratio, 0.29 [95% CI, 0.12-0.67]; P = .004). Relapse was less frequent in patients with lymphoma (risk ratio, 0.27 [95% CI, 0.09-0.80]; P = .019) and in patients treated with rituximab and chemotherapy (risk ratio, 0.31 [95% CI, 0.12-0.79]; P = .014).

CONCLUSIONS

Rituximab is an efficient and well-tolerated therapeutic option in AE, especially in lymphoid malignancies and in the absence of detectable anti-C1-INH antibodies.

Acquired Angioedema Associated with Lymphoproliferative Disorders

Introduction

Acquired angioedema due to C1 esterase inhibitor deficiency (C1INH-AAE) is most associated with lymphoproliferative disorders (LPDs), particularly low-grade B-cell subtypes. The condition remains under-recognized with long diagnostic delays due to various challenges including a lack of awareness of the condition.

Case Presentation

We discuss 4 cases of C1INH-AAE associated with low-grade B-cell LPDs, including various diagnostic and management challenges. As our cases illustrate, constitutional symptoms or overt manifestations of LPD at diagnosis are often absent. Hence, a comprehensive multimodal approach to screening for an underlying B-LPD is important when a diagnosis of acquired angioedema is made. Levels of complement C4, C1q, and C1INH are useful for diagnosing C1INH-AAE and for monitoring disease activity. Changes in these parameters may also indicate relapse of the underlying hematological malignancy. Treating the underlying disorder is important as this commonly leads to clinical improvement with decreased episodes of angioedema and normalization of complement studies.

Conclusion

Awareness of C1INH-AAE can lead to an early diagnosis of hematological malignancies. The absence of constitutional symptoms emphasizes the need for a comprehensive multimodal approach to screening for LPD in C1INH-AAE. C4, C1INH level, and function are useful for monitoring disease activity.

Acquired Angioedema Due to C1-Inhibitor Deficiency (AAE-C1-INH)-A Bicenter Retrospective Study on Diagnosis, Course, and Therapy

BACKGROUND

Acquired angioedema with C1-inhibitor deficiency (AAE-C1-INH) is a rare condition resembling hereditary angioedema (HAE), but with late onset and low C1-inhibitor (C1-INH) due to consumption potentially caused by autoimmune diseases and mainly lymphatic malignancies. Being about 10-fold rarer than HAE, there is limited knowledge and no licensed therapy.

OBJECTIVE

To report clinical and biological data from a newly described population of 20 patients with AAE-C1-INH assessing diagnostic delay, AAE-C1-INH:HAE-ratio, underlying conditions, and therapeutic management in Germany.

METHODS

Retrospective data analysis of 20 patients from 2 angioedema centers in southern Germany.

RESULTS

Median age at symptoms' onset was 64 years (60% females), with predominant swellings of the face (85%) and low levels for C1-INH in almost all patients. The ratio AAE-C1-INH:HAE was 1:9.7. From symptoms' onset to diagnosis of AAE-C1-INH, the median delay was 7.5 months, and between AAE-C1-INH symptoms' onset and diagnosis of the underlying hematological condition (n = 9) it was 4 months (median). Four patients had a history of solid neoplasm, 1 had a papillary thyroid carcinoma as the only potential cause for AAE-C1-INH, with treatment of the malignancy resulting in resolution of AAE-C1-INH. All the symptomatic patients were treated with off-label on-demand icatibant subcutaneously or C1-INH concentrate intravenously, and 6 severely affected patients needed off-label long-term prophylaxis with good symptom control.

CONCLUSIONS

AAE-C1-INH is characterized by late-onset swellings mainly involving the face and low C1-INH levels. Diagnostic delay for AAE-C1-INH is further decreasing despite being about 10-fold rarer than HAE. Patients severely affected without underlying condition or no indication for treatment could benefit from off-label therapy.

A Retrospective Analysis of Long-Term Prophylaxis with Berotralstat in Patients with Hereditary Angioedema and Acquired C1-Inhibitor Deficiency-Real-World Data

Hereditary angioedema (HAE) and acquired C1-inhibitor deficiency (AAE-C1-INH) are orphan diseases. Berotralstat is a recently licensed long-term prophylaxis (LTP) and the first oral therapy for HAE patients. No approved therapies exist for AAE-C1-INH patients. This study is the first to report real-world clinical data of patients with AAE-C1-INH and HAE who received Berotralstat. All patients treated with Berotralstat were included in this retrospective, bi-centric study. Data was collected from patients' attack calendars and the angioedema quality of life (AE-QoL) and angioedema control test (AECT) questionnaires before treatment, and at 3, 6, and 12 months after treatment and was then analyzed. Twelve patients were included, 3 patients with AAE-C1-INH, 7 patients with HAE type I, and 2 patients with HAE-nC1-INH. One patient (HAE I) quit treatment. Berotralstat was associated with fewer attacks in all groups. After 6 months of treatment, a median decrease of attacks per month was noted for HAE type I patients (3.3 to 1.5) and AAE-C1-INH patients (2.3 to 1.0). No aerodigestive attacks were noted for AAE-C1-INH patients. For HAE-nC1-INH patients, a mean decrease from 3.8 to 1.0 was noted (3 months). For HAE I patients, the total AE-QoL lowered a mean of 24.1 points after 6 months, for HAE-nC1-HAE patients 8.0 points, and for AAE-C1-INH patients 13.7 points. AECT scores increased for HAE I patients (mean: 7.1), HAE-nC1-INH patients (9.0), and AAE-C1-INH patients (4.2) after 6 months. Patients with HAE, HAE-nC1-INH, and AAE-C1-INH treated with Berotralstat showed reduced angioedema attacks and improved AE-QoL and AECT scores.

Chronic Urticaria and Angioedema: Masqueraders and Misdiagnoses

Chronic urticaria is a common condition presenting with intensely pruritic wheals. Although individual lesions resolve within 24 hours, by definition, chronic urticaria lasts for a duration of at least 6 weeks. Both spontaneous and inducible forms exist. In the spontaneous variant, chronic urticaria occurs in the absence of clearly identifiable triggers. In chronic inducible urticaria, specific triggers may include dermatographism, cholinergic (heat), cold, exercise, delayed pressure, and solar. Extensive laboratory evaluation for chronic spontaneous urticaria is not required unless indicated by clinical history or physical examination. Angioedema describes sudden onset of localized edema involving the deep layers of the skin and submucosal tissues. It can be seen in isolation or in conjunction with chronic urticaria. Angioedema typically resolves slower than wheals, taking up to 72 hours or longer. Histamine- and bradykinin-mediated forms exist. Both chronic urticaria and angioedema have many mimics, and a broad range of differential diagnoses should be considered. Importantly, an incorrect diagnosis may have significant implications for the additional investigation, treatment, and prognosis of the affected patient. The aim of this article is to discuss the characteristics of chronic urticaria and angioedema, and an approach to the investigation and diagnosis of their mimics.

Management of hereditary angioedema in resource-constrained settings: A consensus statement from Indian subcontinent

Hereditary angioedema (HAE) is an uncommon disorder characterized clinically by recurrent episodes of nonitchy subcutaneous and/or submucosal swellings. The estimated prevalence of HAE is ~ 1: 10,000 to 1: 50,000. There are no prevalence data from India, however, estimates suggest that there are 27,000 to 135,000 patients with HAE in India at present. The majority of these, however, remain undiagnosed. Replacement of plasma-derived or recombinant C1-esterase inhibitor (C1-INH) protein, administered intravenously, is the treatment of choice during the management of acute episodes of angioedema (i.e., "on-demand treatment") and is also useful for short-term prophylaxis (STP) and long-term prophylaxis (LTP). This has been found to be effective and safe even in young children and during pregnancy. Until recently, none of the first-line treatment options were available for "on-demand treatment," STP or LTP in India. As a result, physicians had to use fresh frozen plasma for both "on-demand treatment" and STP. For LTP, attenuated androgens (danazol or stanozolol) and/or tranexamic acid were commonly used. These drugs have been reported to be useful for LTP but are associated with a significant risk of adverse effects. Intravenous pd-C1-INH, the first-line treatment option, is now available in India. However, because there is no universal health insurance, access to pd-C1-INH is a significant challenge. HAE Society of India has developed these consensus guidelines for India and other resource-constrained settings where plasma-derived C1-INH therapy is the only available first-line treatment option for the management of HAE and diagnostic facilities are limited. These guidelines have been developed because it may not be possible for all patients to access the recommended therapy and at the recommended doses as suggested by the international guidelines. Moreover, it may not be feasible to follow the evaluation algorithm suggested by the international guidelines.

C1-inhibitor/C1-inhibitor antibody complexes in acquired angioedema due to C1-inhibitor deficiency

BACKGROUND

Autoantibodies against C1-inhibitor (C1-INH-Ab) have a diagnostic value in acquired angioedema due to C1-inhibitor deficiency (C1-INH-AAE), even though antibodies can circulate in complexes, which can be undetectable by proven methods. Our aim was to measure C1-INH/C1-INH-Ab complexes (CAC) and investigate their connection to C1-INH-Ab and the changes in their titer over time.

RESULTS

19 patients were diagnosed with C1-INH-AAE in the Hungarian Angioedema Center of Reference and Excellence; 79% of them had an underlying disease. Samples were examined with a newly developed in-house complex ELISA method. Patients with high C1-INH-Ab titer had a CAC titer which did not exceed the normal level and the ones with high CAC titer had a C1-INH-Ab titer which did not exceed the normal level. In case of those patients who had C1-INH-Ab and CAC of the same type of immunoglobulin, the increasing titer of C1-INH-Ab went together with the decreasing level of CAC and vice versa. CAC titer was already increased before the diagnosis of the underlying disease.

CONCLUSIONS

Free circulating and complex antibodies are in a dynamically changing equilibrium. CAC measurements can help to predict the development of an underlying disease. The efficiency of the treatment for underlying disease can be monitored by the decreasing CAC titers. Our results show that the CAC can be of important additional information besides the complement panel examination in case of C1-INH-AAE. Measurement of CAC is recommended to be done parallelly with C1-INH-Ab, so as to detect both free and bound antibodies.

Presentation of an extraordinary colic: abdominal pain as the first and only utterance of an acquired C1-inhibitor deficiency

C1-inhibitor deficiency is a rare disease which incorporates acute self-limiting intermittent swelling of the subcutaneous tissue and mucous membranes. Attacks most frequently affect the face and/or the upper airway. Isolated angioedema of the small bowel is an uncommon manifestation and often accompanied by diagnostic delay. In the present case, abdominal pain turned out to be the first and only utterance of an acquired C1-inhibitor deficiency, secondary to a splenic marginal zone lymphoma. Imaging showed wall thickening of the small intestine, ascites and splenomegaly. The abdominal pain and intestinal wall thickening with surrounding ascites on imaging spontaneously resolved each episode within 2-3 days. Gastrointestinal manifestations of angioedema may mimic an acute abdomen, and subsequently one-third of these patients undergo unnecessary surgery prior to a definite diagnosis. This emphasises the importance of considering the diagnosis in case of an 'extraordinary colic'.

Longitudinal experience with treatment of acquired angioedema using tranexamic acid

Background: Acquired angioedema (AAE) is a rare form of angioedema (AE) and is often associated with lymphoproliferative conditions and/or anti-C1 esterase inhibitor (C1-INH) antibodies without clear treatment consensus. Current treatments have been reported to have variable effectiveness with different safety concerns. A large Italian cohort of patients with AAE was previously found to respond well to tranexamic acid (TXA). Herein, we report our experience treating AAE with TXA used as prophylaxis. Objective: The objective was to describe clinical characteristics of patients with AAE and to report our experience with treating AAE with TXA. Methods: A retrospective chart review of patients with AAE (N = 13) from a large practice was conducted to assess characteristics and treatment responses. Patient demographics in addition to C1-INH quantitative, C1-INH functional, C4, and C1q levels; the presence of C1-INH antibodies; and a history of lymphoproliferative disease were extracted. The patients were also characterized by their treatment response to TXA. Results: All the patients were white, with a mean age at diagnosis of 67 years, an average body mass index of 31.3 kg/m², and a male-to-female ratio of 7:6. Nine patients had positive C1-INH antibodies. The patients were on various prophylaxis treatments before TXA, including chemotherapy that targeted malignancy, cyclophosphamide, rituximab, and plasmapheresis. Ultimately, 11 of the 13 patients were on TXA for prophylaxis. At 1, 12, and 24 months after TXA treatment, attacks decreased by 97, 86, and 99%, respectively. One patient developed a deep vein thrombosis and TXA was stopped. Conclusion: These findings demonstrated that treatment of AAE with TXA was effective as prophylaxis for AE attacks. However, potential adverse effects remain a concern, which emphasizes the need for additional options.

Isolated Angioedema: A Review of Classification and Update on Management

OBJECTIVE

The purpose of this article is to review the various types of angioedema including diagnosis and treatment.

DATA SOURCES

PubMed search of articles in the English language various types of angioedema STUDY SELECTION: Articles on the subject matter were selected and reviewed.

RESULTS

Herein, a case based approach is presented for discussing the major types of angioedema including: hereditary angioedema (HAE) TypesI/II and normal complement, acquired angioedema, Angiotensin converting enzyme (ACE) induced angioedema, as well as histaminergic and non-histaminergic angioedema. Emerging treatments of HAE including targets of pre-kalikrein, DNA vector technology replacing C1INH protein, and CRIPSR technology targeting PKK among many others are explored. In addition, other causes as well as mimickers of angioedema are briefly reviewed. Finally, a novel algorithm is proposed to help guide the treating physician through the work up and management of patients with suspected idiopathic angioedema unresponsive to conventional therapy with antihistamines.

CONCLUSION

Over the years, many strides have been made in both understanding the pathophysiology of various types of angioedema as well as expansion of treatment options. It is important for clinicians to be aware of current and emerging treatment options. We provide a novel practical algorithm to guide clinicians in challenging cases of idiopathic angioedema refractory to antihistamines.

Angioedema Due to Acquired Deficiency of C1-Inhibitor: A Cohort Study in Spain and a Comparison With Other Series

BACKGROUND

Data on acquired angioedema due to C1-inhibitor deficiency (C1-INH-AAE) from 4 European countries (France, Italy, Germany, and Hungary) were recently published.

OBJECTIVE

To report data from a group of 50 patients with acquired C1-INH deficiency from Spain, of whom 46 had angioedema, and compare them with other European series.

METHODS

We performed a retrospective observational study of 46 patients with C1-INH-AAE and 4 asymptomatic patients. Clinical and biological characteristics and associated diseases were assessed and compared with other European series.

RESULTS

Women accounted for 73.9% of cases. The prevalence of C1-INH-AAE related to hereditary forms was 1/10.1. Overall, 8.7% patients were aged <40 years. Diagnostic delay was 1.1 years. Angioedema mainly affected the face (91.3%), followed by the oropharynx (63%), extremities (50%), and abdomen (37%). Only 1 patient underwent orotracheal intubation. Erythema marginatum was present in 1 patient. A hematologic disorder was recorded in 50% of patients. Angioedema preceded all benign conditions, mostly monoclonal gammopathy of undetermined significance, but appeared very close to or after malignant hematologic diseases (median, 2.2 and 0.29 years). Autoimmune diseases were associated in 50% (autoimmune thyroiditis, 21.5%; systemic lupus erythematosus, 10.9%). Half of them coexisted with hematologic disorders. Anti-C1-INH antibodies were found in 67% of tested patients and were not related to the associated disease. Long-term prophylaxis was necessary in 52.2%, most of whom responded to tranexamic acid.

CONCLUSIONS

This study emphasizes the possibility of C1-INH-AAE in patients younger than 40 and in autoimmune diseases other than systemic lupus erythematosus such as autoimmune thyroiditis.

The international WAO/EAACI guideline for the management of hereditary angioedema - The 2021 revision and update

Hereditary Angioedema (HAE) is a rare and disabling disease for which early diagnosis and effective therapy are critical. This revision and update of the global WAO/EAACI guideline on the diagnosis and management of HAE provides up-to-date guidance for the management of HAE. For this update and revision of the guideline, an international panel of experts reviewed the existing evidence, developed 28 recommendations, and established consensus by an online DELPHI process. The goal of these recommendations and guideline is to help physicians and their patients in making rational decisions in the management of HAE with deficient C1-inhibitor (type 1) and HAE with dysfunctional C1-inhibitor (type 2), by providing guidance on common and important clinical issues, such as: 1) How should HAE be diagnosed? 2) When should HAE patients receive prophylactic on top of on-demand treatment and what treatments should be used? 3) What are the goals of treatment? 4) Should HAE management be different for special HAE patient groups such as children or pregnant/breast feeding women? 5) How should HAE patients monitor their disease activity, impact, and control? It is also the intention of this guideline to help establish global standards for the management of HAE and to encourage and facilitate the use of recommended diagnostics and therapies for all patients.

The international WAO/EAACI guideline for the management of hereditary angioedema-The 2021 revision and update

Hereditary angioedema (HAE) is a rare and disabling disease for which early diagnosis and effective therapy are critical. This revision and update of the global WAO/EAACI guideline on the diagnosis and management of HAE provides up-to-date guidance for the management of HAE. For this update and revision of the guideline, an international panel of experts reviewed the existing evidence, developed 28 recommendations, and established consensus by an online DELPHI process. The goal of these recommendations and guideline is to help physicians and their patients in making rational decisions in the management of HAE with deficient C1 inhibitor (type 1) and HAE with dysfunctional C1 inhibitor (type 2), by providing guidance on common and important clinical issues, such as: (1) How should HAE be diagnosed? (2) When should HAE patients receive prophylactic on top of on-demand treatment and what treatments should be used? (3) What are the goals of treatment? (4) Should HAE management be different for special HAE patient groups such as children or pregnant/breast-feeding women? and (5) How should HAE patients monitor their disease activity, impact, and control? It is also the intention of this guideline to help establish global standards for the management of HAE and to encourage and facilitate the use of recommended diagnostics and therapies for all patients.

Guidelines for management of hereditary angioedema: What is new? What is missing?

Background: Hereditary angioedema is an autosomal dominant disease that presents with recurrent episodic swelling of the submucosal and/or subcutaneous tissues of the cutaneous, gastrointestinal, and respiratory systems. Evaluation and treatment guidelines have been published nationally and internationally to aid the treating provider. Methods: A review of the most cited and most recent updated guidelines was undertaken to review key points and to explore real-world feasibility of incorporating them into clinical practice. The International World Allergy Organization/European Academy of Allergy and Clinical Immunology (WAO/EAACI) Guideline for the Management of Angioedema - The 2017 Revision and Update, and the consensus reports from the Hereditary Angioedema International Working Group, the Joint Task Force on Practice Parameters focused practice parameter update, and the most recently updated US HAEA Medical Advisory Board 2020 Guidelines for the Management of Hereditary Angioedema were reviewed and summarized. Results: Key points that have been consistent throughout the guidelines include recommendations for evaluation and classification of hereditary angioedema as well as evidence-based guidelines for treatment. Further attention is required on the evaluation and continuous assessment of the burden of illness and quality of life (QoL). Conclusion: The guidelines for management of hereditary angioedema provide a framework for the clinician. However, the physician-patient dialog with regard to the patient disease experience, which includes attack frequency, severity, and Qol, must be continually assessed.

The characteristics of upper airway edema in hereditary and acquired angioedema with C1-inhibitor deficiency

Background

Angioedemas localized in the upper airway are potentially life threatening, and without proper treatment, they may lead to death by suffocation. Upper airway edemas (UAE) in bradykinin‐mediated angioedemas can even be the first symptoms of the disease.

Methods

Our survey was performed with a retrospective long‐term follow‐up method from the medical history of 197 hereditary (C1‐INH‐HAE) and 20 acquired C1‐inhibitor deficiency (C1‐INH‐AAE), 3 factor XII and 3 plasminogen gene mutation (FXII‐HAE, PLG‐HAE) patients treated at our center between 1990 and 2020. The UAE group included edemas localized to the mesopharynx, hypopharynx, and larynx, as narrowing of these anatomical regions can lead to suffocation.

Results

98/197 C1‐INH‐HAE (47 families) and 13/20 C1‐INH‐AAE, 1/3 PLG‐HAE, 1/3 FXII‐HAE patients had experienced UAE at least once according to their medical history. In case of C1‐INH‐HAE patients, in 6/47 families who had undiagnosed ancestors had 13 members who died of suffocation. After the diagnosis, 1‐1 member of two families died of UAE. 44/64 C1‐INH‐HAE patients did not smoke, 20/64 did. The occurrence of UAE was significantly higher in smoker patients. We analyzed 7607 HAE attacks of 56/98 patients. Out of all attacks, the incidence of UAE in the C1‐INH‐HAE group was 4%, and 9.5% in the C1‐INH‐AAE group, respectively.

Conclusion

Early diagnosis is key in bradykinin‐mediated angioedemas cases, since the patient must be provided with adequate treatment; and also it is essential to inform patients about the importance of avoiding the trigger factors and the early symptoms of UAE, as these measures could significantly decrease the incidence of lethal UAEs.

Angioedema Without Wheals: Challenges in Laboratorial Diagnosis

Angioedema is a prevailing symptom in different diseases, frequently occurring in the presence of urticaria. Recurrent angioedema without urticaria (AE) can be hereditary (HAE) and acquired (AAE), and several subtypes can be distinguished, although clinical presentation is quite similar in some of them. They present with subcutaneous and mucosal swellings, affecting extremities, face, genitals, bowels, and upper airways. AE is commonly misdiagnosed due to restricted access and availability of appropriate laboratorial tests. HAE with C1 inhibitor defect is associated with quantitative and/or functional deficiency. Although bradykinin-mediated disease results mainly from disturbance in the kallikrein–kinin system, traditionally complement evaluation has been used for diagnosis. Diagnosis is established by nephelometry, turbidimetry, or radial immunodiffusion for quantitative measurement of C1 inhibitor, and chromogenic assay or ELISA has been used for functional C1-INH analysis. Wrong handling of the samples can lead to misdiagnosis and, consequently, mistaken inappropriate approaches. Dried blood spot (DBS) tests have been used for decades in newborn screening for certain metabolic diseases, and there has been growing interest in their use for other congenital conditions. Recently, DBS is now proposed as an efficient tool to diagnose HAE with C1 inhibitor deficiency, and its use would improve the access to outbound areas and family members. Regarding HAE with normal C1 inhibitor, complement assays’ results are normal and the genetic sequencing of target genes, such as exon 9 of F12 and PLG, is the only available method. New methods to measure cleaved high-molecular-weight kininogen and activated plasma kallikrein have emerged as potential biochemical tests to identify bradykinin-mediated angioedema. Validated biomarkers of kallikrein–kinin system activation could be helpful in differentiating mechanisms of angioedema. Our aim is to focus on the capability to differentiate histaminergic AE from bradykinin-mediated AE. In addition, we will describe the challenges developing specific tests like direct bradykinin measurements. The need for quality tests to improve the diagnosis is well represented by the variability of results in functional assays.

Hereditary Angioedema: Diagnostic Algorithm and Current Treatment Concepts

Hereditary angioedema (HAE) is an uncommon disorder with a global prevalence of approximately 1 in 10,000 to 1 in 50,000 population. This disease is grossly underrecognized in India because of lack of awareness and/or lack of diagnostic facilities. Clinical manifestations include swelling over face, eyes, lips, hands, feet, and genitals, abdominal pain, and life-threatening laryngeal edema. HAE should be suspected in all patients who present with angioedema without wheals and who do not respond to antihistamines and/or steroids. C1 levels, C1-INH levels, and C1-INH function should be checked in all patients suspected to have HAE. C1q levels should be assessed in patients with suspected autoimmune-mediated acquired angioedema. Management of HAE constitutes the treatment of acute attack and short-term and long-term prophylaxis. Because of lack of all first-line recommended medications, the management of HAE in India is a challenging task. Patients are managed using fresh frozen plasma (acute treatment), tranexamic acid, and attenuated androgens (prophylaxis). Even though attenuated androgens have been shown to be effective in the prevention of attacks of HAE, the side effect profile especially in children and in females is a serious concern. Hence, the treatment needs to be individualized considering the risk-benefit ratio of long-term prophylaxis. In this review, we provide an overview of diagnostic strategy for patients with HAE and the current treatment concepts with emphasis on currently available treatment options in resource-constrained settings.

Acquired Angioedema Due to C1 inhibitor Deficiency Caused by Non-Hodgkin Lymphoma in a Patient with Myasthenia Gravis

Acquired angioedema due to C1-inhibitor deficiency is a very rare disorder that usually appears in patients with lymphoproliferative and/or autoimmune diseases. This type of swelling is bradykinin mediated and does not respond to antihistamines, corticosteroids, or epinephrine. The symptoms usually appear in patients older than 40 years with recurrent episodes of angioedema without wheals. The family history is negative. The swelling could affect any tissue, but most frequently is located at the face, lips, tongue, larynx, or extremities. In the gastrointestinal tract, it causes pain, nausea, vomiting, and diarrhea. The upper respiratory airway oedema is a potentially life-threatening condition due to asphyxiation. The oedema attacks may precede the symptoms of the causative disease for months or years. In most cases, the treatment of the underlying disease resolves the angioedema episodes. Here we report a case of C1-INH-AAE caused by non-Hodgkin lymphoma in a patient diagnosed many years before with myasthenia gravis whose angioedema symptoms resolved after the specific treatment of lymphoma.

Increased Risk of Urticaria/Angioedema after BNT162b2 mRNA COVID-19 Vaccine in Health Care Workers Taking ACE Inhibitors

Urticarial eruptions and angioedema are the most common cutaneous reactions in patients undergoing mRNA COVID-19 vaccinations. The vasoactive peptide bradykinin has long been known to be involved in angioedema and recently also in urticaria. Bradykinin is mainly catabolized by angiotensin-converting enzyme (ACE), which is inhibited by ACE inhibitors, a commonly employed class of antihypertensive drugs. We evaluated the risk of developing urticaria/angioedema after inoculation with the BNT162b2 mRNA COVID-19 vaccine in a population of 3586 health care workers. The influences of ACE inhibitors and selected potential confounding variables (sex, age, previous SARS-CoV-2 infection, and allergy history) were evaluated by fitting univariate and multivariable Poisson regression models. The overall cumulative incidence of urticaria/angioedema was 1.8% (65 out of 3586; 95% CI: 1.4–2.3%). Symptoms were mild, and no subject consulted a physician. Subjects taking ACE inhibitors had an adjusted three-fold increased risk of urticaria/angioedema (RR 2.98, 95% CI: 1.12–7.96). When we restricted the analysis to those aged 50 years or more, the adjusted RR was 3.98 (95% CI: 1.44–11.0). In conclusion, our data indicate that subjects taking ACE inhibitors have an increased risk of urticaria/angioedema after vaccination with the BNT162b2 mRNA COVID-19 vaccine. Symptoms are mild and self-limited; however, they should be considered to adequately advise subjects undergoing vaccination.

Where we are with acquired angioedema due to C1 inhibitor deficiency: A systematic literature review

Acquired angioedema due to C1 inhibitor deficiency (C1-INH-AAE) is a rare disease characterized by adult-onset recurrent non-urticarial angioedema with low levels of C1-INH. It is associated with lymphoproliferative disorders, and treatments are off-label with variable success. We conducted a systematic literature review to include patients with C1-INH-AAE identified in PubMed and Embase databases between January 2006 and February 2021. Clinical features of these patients were summarized, and factors associated with disease remission were explored. A total of 121 patients were included in the current study with a median age at diagnosis of 64 years and 45.5% being male. An associated disease was recorded in 94 patients (77.7%), and lymphoproliferative disorder was the most reported (59/94, 62.8%). Anti-C1-INH autoantibodies were present in 45 of 71 patients (63.4%). Factors impacting disease remissions included age (odds ratio [OR] 0.951, 95% confidence interval [CI] 0.909-0.994, p = 0.027), male (OR 0.327, 95% CI 0.124-0.866, p = 0.025), presence of monoclonal gammopathy (OR 0.133, 95% CI 0.041-0.429, p = 0.001), requirement of specific on-demand treatment (OR 0.216, 95% CI 0.066-0.709, p = 0.012) and rituximab use (OR 2.865, 95% CI 1.038-7.911, p = 0.042). A total of nine patients (7.4%) died at last follow up and most were unrelated to C1-INH-AAE. Our results imply that C1-INH-AAE is primarily associated with underlying B or plasma cell abnormalities, and clone-directed therapies could be promising options for its long-term management.

Differences and Similarities in the Mechanisms and Clinical Expression of Bradykinin-Mediated vs. Mast Cell-Mediated Angioedema

Angioedema (AE), transient localized swelling due to extravasated fluid, is commonly classified as mast cell mediator-induced, bradykinin-mediated or of unknown cause. AE often occurs more than once, and it is these recurrent forms of AE that are challenging for patients and physicians, and they are the ones we focus on and refer to as AE in this review. Since effective treatment depends on the causative mediator, reliable and early diagnosis is essential. Although their clinical presentations bear similarities, many forms of angioedema exhibit specific patterns of clinical appearance or disease history that may aid in diagnosis. Here, we describe the most common differences and similarities in the mechanisms and clinical features of bradykinin-mediated and mast cell mediator-induced types of angioedema. We first provide an overview of the diseases that manifest with mast cell mediator-induced versus bradykinin-mediated angioedema as well as their respective underlying pathogenesis. We then compare these diseases for key clinical features, including angioedema location, course and duration of swelling, attack frequency, prevalence and relevance of prodromal signs and symptoms, triggers of angioedema attacks, and other signs and symptoms including wheals, age of onset, and duration. Our review and comparison of the clinical profiles of different types of angioedema incorporate our own clinical experience as well as published information. Our aim is to highlight that mast cell mediator-induced and bradykinin-mediated angioedema types share common features but are different in many aspects. Knowledge of the differences in underlying pathomechanisms and clinical profiles between different types of angioedema can help with the diagnostic approach in affected patients and facilitate targeted and effective treatment.

Lanadelumab Efficacy, Safety, and Injection Interval Extension in HAE: A Real-Life Study

BACKGROUND

Lanadelumab has been available in Germany for the prophylactic treatment of hereditary angioedema since February 2019.

OBJECTIVE

To investigate real-life treatment outcome of lanadelumab and gain practical experience in adapting the therapy to individual patients.

METHODS

The study included 34 patients. In 24 patients with hereditary angioedema and 4 patients with angioedema due to acquired C1-inhibitor deficiency, the previous treatment was switched to lanadelumab. In 6 patients with hereditary angioedema, lanadelumab from the open-label Hereditary Angioedema Long-term Prophylaxis study was continued in regular care. During the transition, patients were monitored using the angioedema control test and the angioedema quality of life questionnaire. At the time at which patients became symptom-free, the dosage interval was increased gradually (+3 days).

RESULTS

On average, the angioedema control test values improved from 7.5 (poorly controlled disease) to 14.9 (well-controlled disease), and all patients showed adequate disease control. All treated patients, except 1 outlier, scored angioedema quality of life questionnaire values representing only a slight reduction in quality of life (mean, 14 points). At the time point of data collection, 9 patients used an average fixed injection interval of 30 days. Twenty-two patients were symptom-free from the beginning of the treatment phase and intended to extend their injection interval from 30 to 32.5 days (median). We recommended reducing the initial dosing interval from 24 to 21 days (median) to 3 patients because of intermediately occurring symptoms.

CONCLUSIONS

Gradual extension of injection intervals of lanadelumab presented in this study can minimize the burden of therapy without losing efficacy.

Managing Chronic Urticaria and Recurrent Angioedema Differently with Advancing Age

Angioedema and urticaria affect people of all ages. Accurate diagnosis and optimum management is essential for healthy aging. Older people continue to experience mast cell-mediated urticaria and angioedema, with a higher prevalence of autoimmune and a lower prevalence of autoallergic disease. Bradykinin-mediated angioedemas are more common in the elderly because of their association with angiotensin-converting enzyme inhibitor (ACEI) treatment. Acquired C1-inhibitor deficiency, another bradykinin-mediated angioedema, occurs predominantly in older people, whereas hereditary angioedema due to C1-inhibitor deficiency continues to cause symptoms, even in old age. Drug-induced angioedemas disproportionately affect older people, the most frequent users of ACEIs, aspirin, and nonsteroidal anti-inflammatory drugs. Accurate diagnosis and targeted treatment prevent unnecessary morbidity and mortality. Second-generation antihistamines with omalizumab if required are effective and well tolerated in older people with mast cell-mediated urticaria. For bradykinin-mediated angioedemas, these drugs are ineffective. C1-inhibitor replacement or blockade of kallikrein or the bradykinin B2 receptor of the contact pathway is required to treat hereditary angioedema and may be considered in other bradykinin-mediated angioedemas, if supportive treatment is insufficient. For aspirin-related angioedema and urticaria, alternative medications or, exceptionally, desensitization may be required.

A follow-up survey of patients with acquired angioedema due to C1-inhibitor deficiency

BACKGROUND

Acquired angioedema due to C1-inhibitor deficiency (C1-INH-AAE) is a rare form of bradykinin-mediated angioedema. It is diagnosed by complement testing; its treatment consists of the management of angioedema (AE) attacks and of underlying disease.

OBJECTIVE

Evaluate the results of the clinical follow-up of patients with C1-INH-AAE.

METHODS

Between 1999 and 2020, 3938 patients with angioedema were evaluated, and 17 diagnosed with acquired C1-INH deficiency were followed-up.

RESULTS

Mean age of the 17 patients was 61 years at diagnosis. In 33%, ACE inhibitors provoked AE attacks. Autoantibodies against C1-INH were detected in 10 patients at diagnosis and in a further patient during follow-up. The AE attacks involved the skin in 70.6%, the upper airways in 41.2% and the tongue/lip in 52.9% of patients. Twelve of the 17 patients had an underlying condition, mainly (n = 11) lymphoproliferative disease. In 10 patients diagnosed with a haematological disorder, AAE symptoms preceded the onset of the latter. One patient has not experienced an AE attack since diagnosis. Twelve patients were treated for angioedema attacks, and 32% of the attacks required acute treatment. PdC1-INH was used to relieve AE attacks, and rituximab for the treatment of underlying disease (in six patients). Six patients had multiple AE attacks before any treatment. The symptom-free period increased in five patients after the on-demand administration of pdC1-INH concentrate and following treatment of the underlying disease in two patients.

CONCLUSION

Early diagnosis of C1-INH-AAE and underlying disease is indispensable to reduce disease burden by introducing appropriate, individualized treatment and regular follow-up.

Acquired Angioedema with C1 Inhibitor Deficiency: Occurrence, Clinical Features, and Management: A Nationwide Retrospective Study in the Czech Republic Patients

INTRODUCTION

Acquired angioedema with C1 inhibitor deficiency (AAE-C1-INH) is rare but a potentially life-threatening disease. There are no official prevalence data, nor approved therapies for this condition.

OBJECTIVE

In this study, we aimed to collect and analyze clinical data on patients with AAE-C1-INH in the Czech Republic.

METHODS

We have conducted a retrospective analysis of AAE-C1-INH patients from Czech referral centers for the treatment of hereditary angioedema with C1 inhibitor deficiency. The inclusion criteria involved recurrent episodes of angioedema with the first manifestation at or after the age of 40, negative family history of angioedema, and C1 inhibitor function 50% or less.

RESULTS

A total of 14 patients (7 males and 7 females) met the inclusion criteria for AAE-C1-INH. The median age of the symptom onset was 59.5 years, and the median diagnosis delay was 1 year. The most common clinical manifestation was facial edema (100%) and upper airway swelling (85.7%). All patients responded to the acute attack treatment with icatibant and plasma-derived or recombinant C1 inhibitor concentrate. Lymphoid malignancy was identified in 9 patients (64%), monoclonal gammopathy of uncertain significance in 3 (21%), and in 1 patient autoimmune disease (ulcerative colitis) was considered causative (7%). We were not able to identify any underlying disease only in 1 patient (7%). In 6 of 7 patients (86%) treated for lymphoma, either a reduction in the frequency of angioedema attacks or both angioedema symptoms' disappearance and complement parameter normalization was observed.

CONCLUSIONS

The prevalence of AAE-C1-INH in the Czech Republic is about 1:760,000. This rare condition occurs in approximately 8% of the patients with angioedema with C1 inhibitor deficiency. AAE-C1-INH is strongly associated with lymphoproliferative disorders, and treating these conditions may improve the control of angioedema symptoms.

Quantitative multiplex profiling of the complement system to diagnose complement-mediated diseases

Objectives

Complement deficiencies are difficult to diagnose because of the variability of symptoms and the complexity of the diagnostic process. Here, we applied a novel ‘complementomics’ approach to study the impact of various complement deficiencies on circulating complement levels.

Methods

Using a quantitative multiplex mass spectrometry assay, we analysed 44 peptides to profile 34 complement proteins simultaneously in 40 healthy controls and 83 individuals with a diagnosed deficiency or a potential pathogenic variant in 14 different complement proteins.

Results

Apart from confirming near or total absence of the respective protein in plasma of complement‐deficient patients, this mass spectrometry‐based profiling method led to the identification of additional deficiencies. In many cases, partial depletion of the pathway up‐ and/or downstream of the absent protein was measured. This was especially found in patients deficient for complement inhibitors, such as angioedema patients with a C1‐inhibitor deficiency. The added value of complementomics was shown in three patients with poorly defined complement deficiencies.

Conclusion

Our study shows the potential clinical utility of profiling circulating complement proteins as a comprehensive read‐out of various complement deficiencies. Particularly, our approach provides insight into the intricate interplay between complement proteins due to functional coupling, which contributes to the better understanding of the various disease phenotypes and improvement of care for patients with complement‐mediated diseases.

The Immunopathology of Complement Proteins and Innate Immunity in Autoimmune Disease

The complement is a powerful cascade of the innate immunity and also acts as a bridge between innate and acquired immune defence. Complement activation can occur via three distinct pathways, the classical, alternative and lectin pathways, each resulting in the common terminal pathway. Complement activation results in the release of a range of biologically active molecules that significantly contribute to immune surveillance and tissue homeostasis. Several soluble and membrane-bound regulatory proteins restrict complement activation in order to prevent complement-mediated autologous damage, consumption and exacerbated inflammation. The crucial role of complement in the host homeostasis is illustrated by association of both complement deficiency and overactivation with severe and life-threatening diseases. Autoantibodies targeting complement components have been described to alter expression and/or function of target protein resulting in a dysregulation of the delicate equilibrium between activation and inhibition of complement. The spectrum of diseases associated with complement autoantibodies depends on which complement protein and activation pathway are targeted, ranging from autoimmune disorders to kidney and vascular diseases. Nevertheless, these autoantibodies have been identified as differential biomarkers for diagnosis or follow-up of disease only in a small number of clinical conditions. For some autoantibodies, a clear relationship with clinical manifestations has been identified, such as anti-C1q, anti-Factor H, anti-C1 Inhibitor antibodies and C3 nephritic factor. For other autoantibodies, the origin and the functional consequences still remain to be elucidated, questioning about the pathophysiological significance of these autoantibodies, such as anti-mannose binding lectin, anti-Factor I, anti-Factor B and anti-C3b antibodies. The detection of autoantibodies targeting complement components is performed in specialized laboratories; however, there is no consensus on detection methods and standardization of the assays is a real challenge. This review summarizes the current panorama of autoantibodies targeting complement recognition proteins of the classical and lectin pathways, associated proteases, convertases, regulators and terminal components, with an emphasis on autoantibodies clearly involved in clinical conditions.

Acquired Angioedema due to C1 Inhibitor Deficiency Preceding Splenic Marginal Zone Lymphoma: Further Insights from Clinical Practice

BACKGROUND

Acquired angioedema due to C1 inhibitor deficiency (AAE-C1-INH) is a very rare disease. In clinical practice, it may be difficult to differentiate AAE-C1-INH from hereditary angioedema due to C1-INH deficiency (HAE-C1-INH). In both conditions, patients are at an increased risk of death from asphyxiation due to upper airway obstruction. The association of AAE-C1-INH with lymphoproliferative and autoimmune diseases, and with presence of anti-C1-INH antibodies has been well documented, and treatment of the underlying condition may result in complete remission of angioedema.

OBJECTIVES

To discuss the clinical evaluation, diagnosis, and treatment outcomes of AAE-C1-INH in the context of the care of 2 patients with recurrent isolated angioedema.

METHODS

Two patients were followed up prospectively at our clinic. Measurements of C3, C4, C1-INH, and C1q levels were carried out by nephelometry, and the functional activity of C1-INH was determined by a chromogenic assay. Hematological investigation included morphological and immunophenotyping analysis of peripheral blood, bone marrow, and spleen histopathology. Sequencing of the 8 exons and adjacent intronic regions of the SERPING1 gene was performed using the Sanger method.

RESULTS

Two patients were diagnosed with AAE-C1-INH associated with splenic marginal zone lymphoma during follow-up.

CONCLUSIONS

Close follow-up, including detailed clinical history, physical examination, and laboratory tests, of our patients with AAE-C1-INH was essential for the early diagnosis and successful treatment of the lymphoproliferative disease, leading to the resolution of the angioedema attacks.

US HAEA Medical Advisory Board 2020 Guidelines for the Management of Hereditary Angioedema

Scientific and clinical progress together with the development of effective novel therapeutic options has engendered multiple important changes in the diagnosis and management of hereditary angioedema (HAE). We now update and extend the 2013 United States Hereditary Angioedema Association Medical Advisory Board guidelines for the treatment and management of HAE. The guidelines are based on a comprehensive literature review with recommendations indicating both the strength of our recommendation and the quality of the underlying evidence. Guidelines are provided regarding the classification, diagnosis, on-demand treatment, prophylactic treatment, special considerations for women and children, development of a comprehensive management and monitoring plan, and assessment of burden of illness for both HAE due to C1 inhibitor deficiency and HAE with normal C1 inhibitor. Advances in HAE treatment now allow the development of management plans that can help many patients with HAE lead a normal life. Achieving this goal requires that physicians be familiar with the diagnostic and therapeutic transformations that have occurred in recent years.

Anaphylaxis for Internists: Definition, Evaluation, and Management, with a Focus on Commonly Encountered Problems

Anaphylaxis is an acute systemic allergic reaction that can be life threatening. In adults, the most common causes of anaphylaxis are foods, drugs, and insect stings. This article reviews the definition, classification, evaluation, differential diagnosis, prognosis, complications, and management of anaphylaxis. Tailored for internists, the article focuses on anaphylactic medication allergies. It provides a guide to optimally evaluate and manage patients with antibiotic allergy using a simple, rapid risk stratification technique, graded antibiotic challenge (test dose), and/or allergist-guided drug desensitization. It also reviews other causes of anaphylaxis that internists are likely to encounter, and an approach to their management.

Bradykinin-Mediated Angioedema: An Update of the Genetic Causes and the Impact of Genomics

Recurrent episodes of bradykinin-mediated angioedema (Bk-AE) can associate with acquired or hereditary conditions, the former most commonly developing secondarily to a pharmacological treatment. Despite successful genomic advances that have led to the identification of a large number of disease genes irrespective of disease prevalence, their application to Bk-AE has barely occurred. As a consequence, the genetic causes of Bk-AE remain poorly understood, obstructing the identification of patient subtypes and the development of precision medicine strategies. This review provides an update of the genetic studies completed to date on the acquired forms, which have almost exclusively focused on Bk-AE secondarily to the angiotensin-converting enzyme inhibitor treatment, and the blooming subdivision of the hereditary forms established by the identification of novel causal genes with next-generation sequencing (NGS) technology-based exome studies in genetically undiagnosed patients. Finally, based on the diverse benefits that are offered by the technology, we present arguments favoring the use of holistic NGS approaches as first-tier genetic tests as a promise to reduce the diagnostic odyssey of patients with suspected hereditary forms of Bk-AE.

Acquired C1-inhibitor deficiency presenting with nephrotic syndrome

Acquired C1-inhibitor (C1-INH) deficiency is a rare and potentially life-threatening disorder, which presents with recurrent attacks of non-pitting oedema to the face, airway, limbs or gastrointestinal tract. It is often associated with underlying B-cell lymphoproliferative disorders. We describe a case of a 73-year-old man with acquired C1-INH deficiency who presented with nephrotic syndrome due to glomerular IgM deposition, secondary to an underlying secretory lymphoplasmacytic lymphoma. Both the acquired C1-INH deficiency and the nephrotic syndrome resolved when the underlying B-cell lymphoma was treated with rituximab and bendamustine, suggesting the underlying lymphoproliferative malignancy was driving both disorders.

Hereditary Angio-Oedema for Dermatologists

Among angio-oedema patients, hereditary angio-oedema (HAE) should not be overlooked. Besides skin swellings, these patients might have very painful abdominal attacks and potentially life-threatening angio-oedema of the upper airway. They will not respond to traditional anti-allergic therapy with antihistamines, corticosteroids, and adrenaline, and instead need specific drugs targeting the kallikrein-kinin pathway. Classically, patients with HAE have a quantitative or qualitative deficiency of the C1 inhibitor (C1INH) due to different mutations in SERPING1, although a new subtype with normal C1INH has been recognised more recently. This latter variant is diagnosed based on clinical features, family history, or molecular genetic testing for mutations in F12, ANGPT1,or PLG.The diagnosis of HAE is often delayed due to a general unfamiliarity with this orphan disease. However, undiagnosed patients are at an increased risk of unnecessary surgical interventions or life-threatening laryngeal swellings. Within the last decade, new and effective therapies have been developed and launched for acute and prophylactic therapy. Even more drugs are under evaluation in clinical trials. It is therefore of utmost importance that patients with HAE are diagnosed as soon as possible and offered relevant therapy with orphan drugs to reduce morbidity, prevent mortality, and improve quality of life.

Anaesthetic management of patients with pre-existing allergic conditions: a narrative review

This narrative review seeks to distinguish the clinical patterns of pre-existing allergic conditions from other confounding non-allergic clinical entities, and to identify the potential related risks and facilitate their perioperative management. Follow-up investigation should be performed after a perioperative immediate hypersensitivity to establish a diagnosis and provide advice for subsequent anaesthetics, the main risk factor for perioperative immunoglobulin E (IgE)-mediated anaphylaxis being a previous uninvestigated perioperative immediate hypersensitivity reaction. The concept of cross-reactivity between drugs used in the perioperative setting and food is often quoted, but usually not supported by evidence. There is no reason to avoid propofol in egg, soy, or peanut allergy. The allergenic determinants have been characterised for fish, shellfish, and povidone iodine, but remain unknown for iodinated contrast agents. Iodinated drugs may be used in seafood allergy. Evidence supporting the risk for protamine allergy in fish allergy and in neutral protamine Hagedorn insulin use is lacking. Conversely, cross-reactivity to gelatin-based colloid may occur in α-gal syndrome. Atopy and allergic asthma along with other non-allergic conditions, such as NSAID-exacerbated respiratory disease, chronic urticaria, mastocytosis, and hereditary or acquired angioedema, are not risk factors for IgE-mediated drug allergy, but there is a perioperative risk associated with the potential for exacerbation of the various conditions.

Angioedema due to acquired C1-inhibitor deficiency: spectrum and treatment with C1-inhibitor concentrate

Background

Acquired angioedema due to C1-inhibitor (C1-INH) deficiency (AAE-C1-INH) is a serious condition that may result in life-threatening asphyxiation due to laryngeal edema. It is associated with malignant B-cell lymphoma and other disorders. The purpose of this study was to describe the characteristics and associated disorders of patients with AAE-C1-INH and assess the efficacy of plasma-derived C1-INH concentrate (pdC1-INH) in the treatment of AAE-C1-INH. Forty-four patients with AAE-C1-INH from the Angioedema Outpatient Service of Mainz were assessed for associated disorders. In 32 of these patients, the duration of swelling attacks was measured before and after treatment with pdC1-INH (Berinert® (CSL Behring, Marburg, Germany)). The time between injection and complete resolution of symptoms and treatment effectiveness was provided by the patients.

Results

The following underlying disorders were present: monoclonal gammopathy of undetermined significance (47.7%), non-Hodgkin lymphoma (27.3%), anti-C1-INH autoantibodies alone (11.4%), and other conditions (4.5%). In 9.1% patients, no associated disorder could be found. AAE-C1-INH led to the detection of lymphoma in 75% of patients with the malignancy. Treatment with pdC1-INH shortened attacks by an average (SD) 54.4 (± 32.8) hours (P < 0.0001). The earlier the attack was treated, the shorter the time between injection and resolution of symptoms (P = 0.0149). A total of 3553 (97.7%) of the 3636 attacks were effectively treated with pdC1-INH as assessed by the patient. The mean (SD) dose per-attack was 787 (± 442) U. pdC1-INH was effective in 1246 (93.8%) of 1329 attacks in 8 patients with anti-C1-INH autoantibodies and in 344 (99.4%) of 346 attacks in 6 patients without autoantibodies. The average (SD) dose per effectively treated attack was 1238.4 (± 578.2) U in patients with anti-C1-INH autoantibodies and 510.2 (± 69.1) U in patients without autoantibodies.

Conclusions

pdC1-INH is highly effective in treating AAE-C1-INH patients and is also effective in the vast majority of attacks in patients with anti-C1-INH autoantibodies. It is fast-acting and reduces attack duration.

[Age-specific aspects in the treatment of angioedema patients]

Manifestation of angioedema can occur at any age. We distinguish between two main subtypes: mast cell mediator-associated angioedema (often with hives) and the non-mast cell mediator-associated angioedema. The patient's history is very important due to the fact that one subtype can be hereditary, but we also have to consider new mutations and even not yet diagnosed patients. Acquired non-mast cell mediator-associated angioedema is rare in children, but very common in adults due to the intake of angiotensin-converting enzyme inhibitors. From a detailed anamneses, classification is very often possible. But especially in childhood, symptoms are often projected onto the gastrointestinal tract, which have to be seen differently. The burden of disease defined as disease activity and quality of life may change in the course of life, but is not always predictable. Therapies are available for all angioedema subtypes in any age. If treatment is necessary, the attacks should be treated early to positively influence duration and severity of the attacks. The management of the patients includes besides information, education of the patient and family members regarding therapy options and prevention of triggers and the repetition of education, especially in case of any change of life circumstances.

[Angioedema prophylaxis]

Angioedema is a spontaneous, edematous swelling of the deep layers of the skin or mucous membrane. Angioedema in the respiratory tract is potentially life-threatening. The classification of angioedema into mast-cell-mediated (e. g. urticaria) or bradykinin-mediated (e. g. hereditary angioedema) is important for correct and rational treatment. Generally, two therapeutic strategies are available for angioedema treatment. On-demand treatment of angioedema symptoms that already have emerged aims to stop the further development of the attack and, thus, limits the severity and duration of the attack. This strategy is well established in the treatment of patients with hereditary angioedema, whereas in chronic spontaneous urticaria on-demand therapy plays no role in the guideline recommendations. In contrast, the therapeutic strategy of prophylaxis aims to prevent the occurrence of spontaneous and induced attacks as far as possible. Prophylaxis is the sole therapy strategy for chronic urticaria and is applied at all stages of the treatment algorithm. In the case of hereditary angioedema, on-demand therapy can be complemented by prophylaxis after careful and individual indication. In hereditary angioedema, prophylaxis is currently gaining in importance due to improved treatment options. Patients who use a prophylactic regime are much less likely to be forced to wait for the unpredictable occurrence of an attack and then to react with an on-demand treatment. Prophylactic treatment takes place at times determined by the patient himself, in contrast to treatment on an as-needed basis. The loss of unpredictability is a decisive moment in improving the quality of life.