This evidence- and consensus-based guideline was developed following the methods recommended by Cochrane and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) working group. The conference was held on 1 December 2016. It is a joint initiative of the Dermatology Section of the European Academy of Allergology and Clinical Immunology (EAACI), the EU-founded network of excellence, the Global Allergy and Asthma European Network (GA²LEN), the European Dermatology Forum (EDF) and the World Allergy Organization (WAO) with the participation of 48 delegates of 42 national and international societies. This guideline was acknowledged and accepted by the European Union of Medical Specialists (UEMS). Urticaria is a frequent, mast cell-driven disease, presenting with wheals, angioedema, or both. The lifetime prevalence for acute urticaria is approximately 20%. Chronic spontaneous urticaria and other chronic forms of urticaria are disabling, impair quality of life and affect performance at work and school. This guideline covers the definition and classification of urticaria, taking into account the recent progress in identifying its causes, eliciting factors and pathomechanisms. In addition, it outlines evidence-based diagnostic and therapeutic approaches for the different subtypes of urticaria.

This update and revision of the international guideline for urticaria was developed following the methods recommended by Cochrane and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) working group. It is a joint initiative of the Dermatology Section of the European Academy of Allergology and Clinical Immunology (EAACI), the Global Allergy and Asthma European Network (GA²LEN) and its Urticaria and Angioedema Centers of Reference and Excellence (UCAREs and ACAREs), the European Dermatology Forum (EDF; EuroGuiDerm), and the Asia Pacific Association of Allergy, Asthma and Clinical Immunology with the participation of 64 delegates of 50 national and international societies and from 31 countries. The consensus conference was held on 3 December 2020. This guideline was acknowledged and accepted by the European Union of Medical Specialists (UEMS). Urticaria is a frequent, mast cell–driven disease that presents with wheals, angioedema, or both. The lifetime prevalence for acute urticaria is approximately 20%. Chronic spontaneous or inducible urticaria is disabling, impairs quality of life, and affects performance at work and school. 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.

The autosomal recessive disorder lipoid proteinosis results from mutations in extracellular matrix protein 1 (ECM1), a glycoprotein expressed in several tissues (including skin) and composed of two alternatively spliced isoforms, ECM1a and ECM1b, the latter lacking exon 7 of this 10-exon gene (ECM1). To date, mutations that either affect ECM1a alone or perturb both ECM1 transcripts have been demonstrated in six cases. However, lipoid proteinosis is clinically heterogeneous with affected individuals displaying differing degrees of skin scarring and infiltration, variable signs of hoarseness and respiratory distress, and in some cases neurological abnormalities such as temporal lobe epilepsy. In this study, we sequenced ECM1 in 10 further unrelated patients with lipoid proteinosis to extend genotype-phenotype correlation and to add to the mutation database. We identified seven new homozygous nonsense or frameshift mutations: R53X (exon 3); 243delG (exon 4); 507delT (exon 6); 735delTG (exon 7); 785delA (exon 7); 892delC (exon 7) and 1190insC (exon 8), as well as two new compound heterozygous mutations: W160X/F167I (exon 6) and 542insAA/R243X (exons 6/7), none of which were found in controls. The mutation 507delT occurred in two unrelated subjects on different ECM1 haplotypes and may therefore represent a recurrent mutation in lipoid proteinosis. Taken with the previously documented mutations in ECM1, this study supports the view that exons 6 and 7 are the most common sites for ECM1 mutations in lipoid proteinosis. Clinically, it appears that mutations outside exon 7 are usually associated with a slightly more severe mucocutaneous lipoid proteinosis phenotype, but neurological features do not show any specific genotype-phenotype correlation.

The purpose of our study was to assess the prevalence and clinical course of patients with chronic idiopathic urticaria (CIU), as well as possible causes or associated findings, laboratory findings and the duration of the disease in patients with chronic urticaria (CU). We retrospectively reviewed the 450 case record forms of patients with CU and/or angioedema who attended the Department of Dermatology, Siriraj Hospital, during the period 2000-2004. Of 450 patients with CU, 337 patients (75%) were diagnosed as CIU. Forty-three patients (9.5%) had physical urticaria, while 17 patients (3.8%) had infectious causes. Other possible causes were food, thyroid diseases, atopy, drugs, dyspepsia and collagen vascular diseases. In eighty-nine percent of patients, no abnormalities were detected at the time of physical examination. The most common abnormal laboratory finding was minimal elevation of the erythrocyte sedimentary rate (42%). In 61 patients, autologous serum skin tests had been done. Fifteen patients (24.5%) had positive results i.e. autoimmune urticaria. Anti-thyroglobulin and anti-microsomal antibodies were positive in 16 % and 12% of CIU patients respectively. After 1 year from the onset of the symptoms, 34.5% of CIU patients were free of symptoms and after 1.2 years from the onset of the symptoms, 56.5% of autoimmune urticaria patients were free of symptoms. The median disease duration of CIU and autoimmune urticaria were 390 days and 450 days respectively. Our study provided an overview of CU and CIU in a large series of Thai patients, based on etiological aspects and clinical courses.

Summary Chronic urticaria (CU) affects about 1% of the world population of all ages, mostly young and middle‐aged women. It usually lasts for several years (> 1 year in 25–75% of patients) and often takes > 1 year before effective management is implemented. It presents as chronic spontaneous urticaria (CSU), chronic inducible urticaria (CIndU) or both in the same person. More than 25% of cases are resistant to H1‐antihistamines, even at higher doses, and third‐ and fourth‐line therapies (omalizumab and ciclosporin) control the disease only in two‐thirds of H1‐antihistamine‐resistant patients. Here we review the impact of CU on different aspects of patients’ quality of life and the burden of this chronic disease for the patient and society. CU may have a strong impact on health‐related quality of life (HRQoL), particularly when CSU is associated with angio‐oedema and/or CIndU (Dermatology Life Quality Index > 10 in 30% of patients). Comorbidities, such as anxiety and depression, which are present in more than 30% of patients with CSU, compound HRQoL impairment. Severe pruritus and the unpredictable occurrence of weals and angio‐oedema are responsible for sleep disorders; sexual dysfunction; limitations on daily life, work and sports activities; interfering with life within the family and in society; and patients’ performance at school and work (6% absenteeism and 25% presenteeism). Apart from treatment costs, with annual values between 900 and 2400 purchasing power parity dollars (PPP$) in Europe and the USA, CU is associated with a high consumption of medical resources and other indirect costs, which may reach a total annual cost of PPP$ 15 550.

Angioedemaan intermittent, localized and self-limiting swelling of the subcutaneous or submucosal tissue, due to a temporary increase in vascular permeability, causing tingling, burning, tightness and, sometimes, pain.

Cold urticaria (ColdU) is a common form of chronic inducible urticaria characterized by the development of wheals, angioedema or both in response to cold exposure. Recent research and guideline updates have advanced our understanding and management of ColdU. Today, its pathophysiology is thought to involve the cold‐induced formation of autoallergens and IgE to these autoallergens, which provoke a release of proinflammatory mediators from skin mast cells. The classification of ColdU includes typical and atypical subtypes. We know that cold‐induced wheals usually develop on rewarming and resolve within an hour and that anaphylaxis can occur. The diagnosis relies on the patient's history and cold stimulation testing. Additional diagnostic work‐up, including a search for underlying infections, should only be done if indicated by the patient's history. The management of ColdU includes cold avoidance, the regular use of nonsedating antihistamines and the off‐label use of omalizumab. However, many questions regarding ColdU remain unanswered. Here, we review what is known about ColdU, and we present important unanswered questions on the epidemiology, underlying pathomechanisms, clinical heterogeneity and treatment outcomes. Our aim is to guide future efforts that will close these knowledge gaps and advance the management of ColdU.

Introduction The COVID‐19 pandemic dramatically disrupts health care around the globe. The impact of the pandemic on chronic urticaria (CU) and its management are largely unknown. Aim To understand how CU patients are affected by the COVID‐19 pandemic; how specialists alter CU patient management; and the course of CU in patients with COVID‐19. Materials and Methods Our cross‐sectional, international, questionnaire‐based, multicenter UCARE COVID‐CU study assessed the impact of the pandemic on patient consultations, remote treatment, changes in medications, and clinical consequences. Results The COVID‐19 pandemic severely impairs CU patient care, with less than 50% of the weekly numbers of patients treated as compared to before the pandemic. Reduced patient referrals and clinic hours were the major reasons. Almost half of responding UCARE physicians were involved in COVID‐19 patient care, which negatively impacted on the care of urticaria patients. The rate of face‐to‐face consultations decreased by 62%, from 90% to less than half, whereas the rate of remote consultations increased by more than 600%, from one in 10 to more than two thirds. Cyclosporine and systemic corticosteroids, but not antihistamines or omalizumab, are used less during the pandemic. CU does not affect the course of COVID‐19, but COVID‐19 results in CU exacerbation in one of three patients, with higher rates in patients with severe COVID‐19. Conclusions The COVID‐19 pandemic brings major changes and challenges for CU patients and their physicians. The long‐term consequences of these changes, especially the increased use of remote consultations, require careful evaluation.