Hereditary angioedema due to C1-inhibitor deficiency (C1-INH-HAE type I) or dysfunction (C1-INH-HAE type II) is a rare disease characterized by recurrent episodes of edema with an estimated frequency of 1:50,000 in the global population without racial or gender differences. In this study we present the results of a nationwide survey of C1-INH-HAE patients referring to 17 Italian centers, the Italian network for C1-INH-HAE, ITACA. Italian patients diagnosed with C1-INH-HAE from 1973 to 2013 were included in the study. Diagnosis of C1-INH-HAE was based on family and/or personal history of recurrent angioedema without urticaria and on antigenic and/or functional C1-INH deficiency. 983 patients (53% female) from 376 unrelated families were included in this survey. Since 1973, 63 (6%) patients diagnosed with C1-INH-HAE died and data from 3 patients were missing when analysis was performed. Accordingly, the minimum prevalence of HAE in Italy in 2013 is 920:59,394,000 inhabitants, equivalent to 1:64,935. Compared to the general population, patients are less represented in the early and late decades of life: men start reducing after the 5th decade and women after the 6th. Median age of patients is 45 (IQ 28-57), median age at diagnosis is 26 years (IQ 13-41). C1-INH-HAE type 1 are 87%, with median age at diagnosis of 25 (13-40); type 2 are 13% with median age at diagnosis of 31 (IQ 16-49). Functional C1INH is ≤50% in 99% of patients. Antigen C1INH is ≤50% in 99% of type 1. C4 is ≤50% in 96% of patients. The chance of having C1-INH-HAE with C4 plasma levels >50% is < 0.05. This nationwide survey of C1-INH-HAE provides for Italy a prevalence of 1:64,935. C1-INH-HAE patients listed in our database have a shorter life expectancy than the general population. An increased awareness of the disease is needed to reduce this discrepancy. Measurement of C4 antigen can exclude diagnosis of C1-INH-HAE with an accuracy > 95%. This parameter should be therefore considered for initial screening in differential diagnosis of angioedema.

This update and revision of the international guideline for urticaria was developed in accordance with the methods recommended by Cochrane and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) working group. It is an initiative of the Global Allergy and Asthma Excellence Network (GA ² LEN) and its Urticaria and Angioedema Centers of Reference and Excellence (UCAREs and ACAREs), with the participation of 210 delegates from 107 national and international societies, from 59 countries. The consensus conference was held on December 6th, 2024. This guideline was acknowledged and accepted by the European Union of Medical Specialists (UEMS). Urticaria is a frequent, mast cell‐driven disease, defined by a rapid appearance of wheals, angioedema, or both. The lifetime prevalence of acute urticaria is estimated to be approximately 20%. Chronic urticaria, categorized as either chronic spontaneous urticaria or chronic inducible urticaria, is disabling, impairs quality of life, and affects performance at work and school, however, novel therapies are available. This updated version of the international guideline for urticaria covers the definition and classification of urticaria and outlines expert‐guided and evidence‐based diagnostic and therapeutic approaches for the different subtypes of urticaria.

Melkersson–Rosenthal syndrome (MRS) is a rare, neuro-mucocutaneous disease which presents as orofacial swelling, facial palsy and fissured tongue. These symptoms may occur simultaneously or, more frequently, with a oligosymptomatic or monosymptomatic pattern. Swelling, that is the most common initial finding, may mimic hereditary or acquired angioedema, a disorder caused by histamine or bradykinin-mediated plasma-leakage affecting subcutaneous and/or submucosal tissue. The differential diagnosis of MRS includes also chronic inflammatory and infective diseases characterized by granulomatous infiltration, as well as rosacea, contact dermatitis, allergic reactions and Bell’s palsy. A 71-year old, non-allergic female patient with no familial and personal history of angioedema presented, a few days after a possible herpes simplex or varicella-zoster virus infection, with monolateral facial paraesthesia and lower lip edema. After temporary remission of symptoms on oral steroids and antihistamines, she showed swelling recurrence refractory to valaciclovir therapy and a subsequent course of antihistamines. The clinical picture and a previous history of non-Hodgkin lymphoma prompted us to rule out an acquired form of paraneoplastic, C1-inhibitor (C1-INH) deficiency: C1q and both antigen and functional C1-INH tested normal, whilst we found low plasma levels of C3 and C4 possibly related to the parallel detection of antiphospholipid antibodies. Thus, we hypothesized a non-histaminergic, idiopathic form of angioedema and planned further therapy with tranexamic acid and the leukotriene receptor antagonist montelukast. Treatment failure with both drugs finally suggested a Melkersson–Rosenthal syndrome, which was confirmed by histologic findings of non caseating granulomas on lip biopsy. Melkersson–Rosenthal syndrome may occur with rather non-specific symptoms and overlap with alternative conditions, including recurrent angioedema. No specific biomarkers for MRS exist and clinical diagnosis is often of exclusion. The finding of complement or immune alterations, as in our patient, may be further confounding and justify the need for skin or mucosal biopsy to establish a correct diagnosis and prescribe targeted therapy.

Hereditary angioedema with C1-inhibitor deficiency (C1-INH-HAE) is characterized by recurrent edema of unpredictable frequency and severity. Stress, anxiety, and low mood are among the triggering factors most frequently reported. Impaired regulation and processing of emotions, also known as alexithymia, may influence outcomes. The aim of this study was to confirm the presence of alexithymia and stress in children with C1-INH-HAE, to determine whether they are also present in children affected by other chronic diseases, and to investigate their relationship with C1-INH-HAE severity. Data from children with C1-INH-HAE (n = 28) from four reference centers in Italy were compared with data from children with type 1 diabetes (T1D; n = 23) and rheumatoid arthritis (RA; n = 25). Alexithymia was assessed using the Alexithymia Questionnaire for Children scale; perceived stress was assessed using the Coddington Life Event Scale for Children (CLES-C). Mean age (standard deviation [SD]) in the C1-INH-HAE, T1D, and RA groups was 11.8 (3.3), 11.7 (2.9), and 11.1 (2.6) years, respectively. Mean C1-INH-HAE severity score was 5.9 (2.1), indicating moderate disease. Alexithymia scores were similar among disease groups and suggestive of difficulties in identifying and describing emotions; CLES-C scores tended to be worse in C1-INH-HAE children. C1-INH-HAE severity was found to correlate significantly and positively with alexithymia (p = 0.046), but not with perceived stress. Alexithymia correlated positively with perceived stress. Alexithymia is common in children with chronic diseases. In C1-INH-HAE, it may result in increased perceived stress and act as a trigger of edema attacks. Comprehensive management of C1-INH-HAE children should consider psychological factors.

Hereditary angioedema (HAE) with C1 inhibitor deficiency is a rare disease characterized by unpredictable episodes of tissue swelling (angioedema), which, in most cases, occur first under the age of 18 years, and entail a significant burden of disease not only for the patients but also for their families. Clinical symptoms of HAE are not specific, which may cause difficulties in differential diagnosis. Additionally, if not appropriately treated, HAE attacks can be life‐threatening. The international HAE guidelines published so far have focused mainly on adults. A guideline that refers to the age‐specific characteristics of pediatric patients, both in terms of diagnosis and management, was therefore needed. The International Steering Committee and Taskforce developed recommendations and provided evidence‐based grading based on expert opinion and strength of evidence. Recommendations were presented to, discussed, and electronically voted by healthcare professionals during the 14th C1 Inhibitor Deficiency and Angioedema Workshop in Budapest, Hungary, 2025. This international guideline will ensure early diagnosis, standardized and up‐to‐date treatment, and promote the availability of effective therapies for all pediatric patients affected with this rare disease. It also draws attention to the importance of establishing HAE centers and registries, which solicit specialist care and research of the disease.