S3 guideline: Diagnosis and treatment of epidermal necrolysis (Stevens-Johnson syndrome and toxic epidermal necrolysis) - Part 2: Supportive therapy of EN in the acute and post-acute stages.

Stevens-Johnson syndrome and toxic epidermal necrolysis (SJS/TEN) are rare, predominantly drug-induced, acute life-threatening diseases of skin and mucosae. SJS and TEN are nowadays considered as variants of one disease entity with varying degrees of severity called epidermal necrolysis (EN). EN is associated with high morbidity and mortality and constitutes a major disease burden for affected patients. The guideline "Diagnosis and treatment of epidermal necrolysis (Stevens-Johnson syndrome and toxic epidermal necrolysis)" was developed under systematic consideration of existing scientific literature and in a formal consensus process according to regulations issued by the Association of Scientific Medical Societies in Germany (AWMF) to establish an evidence-based framework to support clinical decision-making. The interdisciplinary guideline commission consisted of representatives from various specialist societies and of patient representatives. The guideline is aimed at specialists in the fields of dermatology, ophthalmology, plastic surgery, intensive care, and pediatrics in hospitals and offices, as well as other medical specialties involved in the diagnosis and treatment of EN. The guideline is also aimed at patients, their relatives, insurance funds, and policymakers. The second part is concerned with the topics of supportive therapy in the acute phase of EN and outpatient follow-up treatment.

S3 guideline: Diagnosis and treatment of epidermal necrolysis (Stevens-Johnson syndrome and toxic epidermal necrolysis) - Part 1: Diagnosis, initial management, and immunomodulating systemic therapy.

Stevens-Johnson syndrome and toxic epidermal necrolysis (SJS/TEN) are rare, predominantly drug-induced, acute, life-threatening diseases of skin and mucosae. SJS and TEN are nowadays considered variants of one disease entity with varying degrees of severity called epidermal necrolysis (EN). EN is associated with high morbidity and mortality and constitutes a major disease burden for affected patients. The guideline "Diagnosis and treatment of epidermal necrolysis (Stevens-Johnson syndrome and toxic epidermal necrolysis)" was developed under systematic consideration of existing scientific literature and in a formal consensus process according to regulations issued by the Association of Scientific Medical Societies in Germany (AWMF) to establish an evidence-based framework to support clinical decision-making. The interdisciplinary guideline commission consisted of representatives from various specialist societies and patient representatives. The guideline is aimed at specialists in the fields of dermatology, ophthalmology, plastic surgery, intensive care, and pediatrics in hospitals and offices, as well as other medical speciallved in the diagnosis and treatment of EN. The guideline is also aimed at patients, their relatives, insurance funds, and policymakers. This first part focuses on the diagnostic aspects, the initial management as well as the immunomodulating systemic therapy.

Basophil activation test in Hymenoptera venom allergy.

Before starting venom-specific immunotherapy (VIT), systemic sting reactions to Hymenoptera venoms require allergological workup in order to prove an IgE-mediated reaction and to identify the culprit insect venom. In addition to skin tests and the determination of specific IgE antibodies, the basophil activation test (BAT) using flow cytometry has emerged as a powerful tool and sensitive marker for this purpose in recent years. BAT seems to have a better informative value in terms of clinical relevance compared to the other tests. In Hymenoptera venom allergies, BAT is particularly useful for the diagnosis of cases with unclear or contradictory history and sensitization profile. Its results are associated with adverse reactions during VIT and efficacy of VIT and therefore have a certain predictive value for side effects and treatment failure of VIT. In research, it is mainly used to characterize the allergenic components of Hymenoptera venoms. This review article focuses on these topics.

Harmonization of Diagnostic Criteria in Mastocytosis for Use in Clinical Practice: WHO vs ICC vs AIM/ECNM.

Mastocytosis is a clonal myeloid disorder defined by an increase and accumulation of mast cells (MCs) in one or multiple organ systems. The complex pathology of mastocytosis results in variable clinical presentations, courses, and outcomes. The World Health Organization (WHO) divides the disease into cutaneous mastocytosis (CM), several forms of systemic mastocytosis (SM), and MC sarcoma. In most patients with SM, a somatic KIT mutation, usually D816V, is identified. Patients diagnosed with CM or nonadvanced SM, including indolent SM, have a near-normal life expectancy, whereas those with advanced SM, including aggressive SM and MC leukemia, have limited life expectancy. Since 2001, a multidisciplinary consensus group consisting of experts from the European Competence Network on Mastocytosis and the American Initiative in Mast Cell Diseases has supported the field by developing diagnostic criteria for mastocytosis. These criteria served as the basis for the WHO classification of mastocytosis over 2 decades. More recently, an International Consensus Classification group proposed slightly modified diagnostic criteria and a slightly revised classification. In this article, these changes are discussed. Furthermore, we propose harmonization among the proposals of the American Initiative in Mast Cell Diseases/European Competence Network on Mastocytosis consensus group, WHO, and the International Consensus Classification Group. Such harmonization will facilitate comparisons of retrospective study results and the conduct of prospective trials.

"Delabeling" by direct provocation testing in children and adolescents with a suspected history of a delayed reaction to ß-lactam antibiotics: Consensus paper of Gesellschaft für pädiatrische Allergologie und Umweltmedizin (GPAU), Deutsche Gesellschaft für Allergologie und klinische Immunologie (DGAKI), and Ärzteverband deutscher Allergologen (ÄDA).

BACKGROUND: Approximately 10% of European children are classified as allergic to drugs. In the majority of these children, no allergy to ß-lactam antibiotics (BLA) can be found. In most cases, the exanthema is caused by the infection. MATERIALS AND METHODS: The objective of this paper is to describe the causes and consequences of a misdiagnosis of drug allergy. We propose a method for establishing a correct diagnosis in the case of a history of a delayed reaction during treatment with a BLA. For this purpose, a proposal was discussed via e-mail communication, and consensus was reached among the members of the drug allergy working groups of the participating medical societies. RESULTS: The suspicion of a BLA allergy based on the medical history alone can have a negative impact on future antibiotic treatment. Exanthema associated with febrile infections not related to drug administration is a frequent finding in children. This makes it all the more important to be able to recommend a standardized procedure for clarification in children and adolescents with suspected hypersensitivity reactions. The medical history should be the basis on which to diagnose either a drug allergy or another possible differential diagnosis. A mild maculopapular exanthema (MPE) can be an expression of a drug allergy or a nonspecific viral exanthema. Uncomplicated MPE is not associated with significant systemic involvement, and there is no involvement of the mucous membranes or cutaneous blistering. Only a small number of children with uncomplicated MPE show positive skin tests and only ~ 7 - 16% of suspected BLA diagnoses can be confirmed by provocation tests. Thus, in children with uncomplicated MPE, drug provocation can be performed in an outpatient setting even without prior skin testing. This paper presents a 3-day outpatient direct provocation scheme for BLA delabeling in children with uncomplicated MPE. CONCLUSION: Many children and adolescents are unnecessarily denied treatment with BLA after an uncomplicated MPE while being treated with a BLA.

Test Panel of Hidden Allergens for "Idiopathic Anaphylaxis" Reveals Wheat Allergy Dependent on Augmentation Factors as Common Final Diagnosis.

BACKGROUND: Idiopathic anaphylaxis (IA) is an unresolved concern. Hidden allergens may be relevant in IA and in nonsteroidal anti-inflammatory drug hypersensitivity (NSAID-HS). OBJECTIVE: To identify hidden elicitors for IA and NSAID-HS by a skin prick test (SPT) (13 allergens) and allergen-specific IgE (sIgE) panel (12 allergens) and to determine the value of each tested allergen. METHODS: We retrospectively included all patients from 2018 to 2021 referred with a suspicion of IA or NSAID-HS by history in whom SPT and/or sIgE to allergens of the IA panel were performed. Patient characteristics from patients' records included comorbidities, history and symptoms of anaphylaxis, serum baseline tryptase level, total IgE level, SPT, sIgE, challenge results, and final diagnoses. RESULTS: A total of 134 patients (77 female, mean age 39.7 ± 14.6 years) were included. Median serum baseline tryptase and total IgE levels were 4.23 µg/L and 133.5 kU/L, respectively. Allergologic workup with the IA panel resulted in positive SPT and sIgE in 61 (47%) and 66 (60%) patients, respectively. In those, confirmation or exclusion of allergy, mostly by challenge, led to a definitive diagnosis in 61 of 134 patients (46%). Skin prick test was most frequently positive to gluten (22.4%) and sIgE to ω5-gliadin (21.6%), which correlated with the history (r = 0.310, P < .001; and r = 0.407, P < .001, respectively). In 28 of 134 patients (21%) with initially suspected IA or NSAID-HS, challenges confirmed occult food allergy in which wheat allergy dependent on augmentation factors was the most frequent cause of anaphylaxis (19%). CONCLUSIONS: Wheat allergy dependent on augmentation factors should be considered in all patients with anaphylaxis of unknown cause or after NSAID intake.

Prevalence of hypersensitivity reactions in various forms of mastocytosis: A pilot study of 2485 adult patients with mastocytosis collected in the ECNM registry.

BACKGROUND: Hypersensitivity reactions (HR) are common in mastocytosis. However, little is known about triggers and risk factors. The registry of the European Competence Network on Mastocytosis (ECNM) enables reliable studies in a larger cohort of mastocytosis patients. We assessed prevalence, triggers and risk factors of HR in adults with mastocytosis in the ECNM registry. METHODS: Data were collected in 27 ECNM centers. We analyzed potential triggers (Hymenoptera venoms, food, drug, inhalant and others) and risk factors at diagnosis and during follow-up. The study group consisted of 2485 adults with mastocytosis, 1379 women (55.5%) and 1106 men (44.5%). Median age was 48.2 years (range 18-91 years). RESULTS: Nine hundred and forty eight patients (38.1%) reported one or more HR`. Most common triggers were Hymenoptera venoms in cutaneous mastocytosis (CM) and indolent systemic mastocytosis (ISM), whereas in advanced SM (advSM), most common elicitors were drugs, including nonsteroidal anti-inflammatory agents and penicillin. In multivariate analyses, tryptase level < 90 ng/mL, <15% infiltration by mast cells in bone marrow biopsy-sections, and diagnosis of ISM were identified as independent risk factors for HR. For drug-induced HR, prominent risk factors were advSM and high tryptase levels. New reactions were observed in 4.8% of all patients during 4 years follow-up. CONCLUSIONS: HR are mainly triggered by Hymenoptera venoms in patients with CM and ISM and by drugs in patients with advSM. Tryptase levels <90 ng/mL, mast cell bone marrow infiltration <15%, and WHO category ISM are predictors of HR. New HR occur in 4.8% of all patients within 4 years.

Basophil activation in insect venom allergy: comparison of an established test using liquid reagents with a test using 5-color tubes with dried antibody reagents.

BACKGROUND: Flow cytometry-based basophil activation tests (BAT) have been performed with various modifications, differing in the use of distinct identification and activation markers. Established tests use liquid reagents while a new development involves the use of tubes with dried antibody reagents. The aim of this pilot study was to compare these two techniques in patients with insect venom allergy. METHODS: Seventeen patients with an insect venom allergy were included in the study. The established "BAT 1" utilizes conventional antibody solutions of anti-CCR3 for basophil identification and anti-CD63 to assess basophil activation, whereas "BAT 2" uses dried anti-CD45, anti-CD3, anti-CRTH2, anti-203c and anti-CD63 for identification and activation measurement of basophils. Negative and positive controls as well as incubations with honey bee venom and yellow jacket venom at three concentrations were performed. RESULTS: Seven patients had to be excluded due to low basophil counts, high values in negative controls or negative positive controls. For the remaining 10 patients the overall mean (± SD) difference in activated basophils between the two tests was 0.2 (± 12.2) %P. In a Bland-Altman plot, the limit of agreement (LoA) ranged from 24.0 to -23.7. In the qualitative evaluation (value below/above cut-off) Cohen's kappa was 0.77 indicating substantial agreement. BAT 2 took longer to perform than BAT 1 and was more expensive. CONCLUSION: The BAT 2 technique represents an interesting innovation, however, it was found to be less suitable compared to an established BAT for the routine diagnosis of insect venom allergies.

Serum chemistry profiling and prognostication in systemic mastocytosis: a registry-based study of the ECNM and GREM.

ABSTRACT: Certain laboratory abnormalities correlate with subvariants of systemic mastocytosis (SM) and are often prognostically relevant. To assess the diagnostic and prognostic value of individual serum chemistry parameters in SM, 2607 patients enrolled within the European Competence Network on Mastocytosis and 575 patients enrolled within the German Registry on Eosinophils and Mast Cells were analyzed. For screening and diagnosis of SM, tryptase was identified as the most specific serum parameter. For differentiation between indolent and advanced SM (AdvSM), the following serum parameters were most relevant: tryptase, alkaline phosphatase, ß2-microglobulin, lactate dehydrogenase (LDH), albumin, vitamin B12, and C-reactive protein (P < .001). With regard to subvariants of AdvSM, an elevated LDH of ≥260 U/L was associated with multilineage expansion (leukocytosis, r = 0.37, P < .001; monocytosis, r = 0.26, P < .001) and the presence of an associated myeloid neoplasm (P < .001), whereas tryptase levels were highest in mast cell leukemia (MCL) vs non-MCL (308µg/L vs 146µg/L, P = .003). Based on multivariable analysis, the hazard-risk weighted assignment of 1 point to LDH (hazard ratio [HR], 2.1; 95% confidence interval [CI], 1.1-4.0; P = .018) and 1.5 points each to ß2-microglobulin (HR, 2.7; 95% CI, 1.4-5.4; P = .004) and albumin (HR, 3.3; 95% CI, 1.7-6.5; P = .001) delineated a highly predictive 3-tier risk classification system (0 points, 8.1 years vs 1 point, 2.5 years; ≥1.5 points, 1.7 years; P < .001). Moreover, serum chemistry parameters enabled further stratification of patients classified as having an International Prognostic Scoring System for Mastocytosis-AdvSM1/2 risk score (P = .027). In conclusion, serum chemistry profiling is a crucial tool in the clinical practice supporting diagnosis and prognostication of SM and its subvariants.

Detection of Sensitization Profiles with Cellular In Vitro Tests in Wheat Allergy Dependent on Augmentation Factors (WALDA).

Wheat allergy dependent on augmentation factors (WALDA) is the most common gluten allergy in adults. IgE-mediated sensitizations are directed towards ω5-gliadin but also to other wheat allergens. The value of the different in vitro cellular tests, namely the basophil activation test (BAT) and the active (aBHRA) and passive basophil histamine-release assays (pBHRA), in the detection of sensitization profiles beyond ω5-gliadin has not been compared. Therefore, 13 patients with challenge-confirmed, ω5-gliadin-positive WALDA and 11 healthy controls were enrolled. Specific IgE (sIgE), skin prick tests, BATs, aBHRA, and pBHRA were performed with allergen test solutions derived from wheat and other cereals, and results were analyzed and compared. This study reveals a distinct and highly individual reactivity of ω5-gliadin-positive WALDA patients to a range of wheat allergens beyond ω5-gliadin in cellular in vitro tests and SPT. In the BAT, for all tested allergens (gluten, high-molecular-weight glutenin subunits, α-amylase/trypsin inhibitors (ATIs), alcohol-free wheat beer, hydrolyzed wheat proteins (HWPs), rye gluten and secalins), basophil activation in patients was significantly higher than in controls (p = 0.004-p < 0.001). Similarly, significant histamine release was detected in the aBHRA for all test substances, exceeding the cut-off of 10 ng/mL in all tested allergens in 50% of patients. The dependency of tests on sIgE levels against ω5-gliadin differed; in the pBHRA, histamine release to any test substances could only be detected in patients with sIgE against ω5-gliadin ≥ 7.7 kU/L, whereas aBHRA also showed high reactivity in less sensitized patients. In most patients, reactivity to HWPs, ATIs, and rye allergens was observed. Additionally, alcohol-free wheat beer was first described as a promising test substance in ω5-gliadin-positive WALDA. Thus, BAT and aBHRA are valuable tools for the identification of sensitization profiles in WALDA.

T-Cell Subtypes and Immune Signatures in Cutaneous Immune-Related Adverse Events in Melanoma Patients under Immune Checkpoint Inhibitor Therapy.

Immune checkpoint inhibition (ICI) improves outcomes in melanoma patients, but associated T-cell activation frequently leads to immune-related cutaneous adverse events (cutAEs). To dynamically identify T-cell subtypes and immune signatures associated with cutAEs, a pilot study was performed in stage III-IV melanoma patients using blood samples for flow cytometry and cytokine analysis. Blood samples were taken from patients before initiation of ICI (naive), at the onset of a cutAE, and after 6 months of ICI treatment. Overall, 30 patients were treated either with anti-PD1 monotherapy or with anti-PD-1/anti-CTLA-4 combination therapy. Flow cytometry analysis of PBMCs showed that ICI induced an overall shift from a Th2 towards a Th1 profile. Twelve patients (40%) developed cutAEs, which were associated with increased Th22 cells and Th17 cells, supported by a tendency to have elevated Th17/Th22-associated cytokines such as IL-17A, IL-22 and IL-23 levels in the plasma. Cytokine signatures specific for urticaria and T-cell-mediated cutAEs were identified in the plasma of patients by a bead-based assay. IL-10 was elevated in non-responders and, interestingly, during cutAEs. In conclusion, we identified distinct immune signatures based on the Th17/Th22 pathway in cutAEs, both in PBMCs and plasma. In addition, our finding of upregulated IL-10 during cutAEs supports the notion of treating these patients early and adequately to avoid implications for the overall outcome.

Targeting histamine receptor 4 in cholinergic urticaria with izuforant (LEO 152020): results from a phase IIa randomized double-blind placebo-controlled multicentre crossover trial.

BACKGROUND: Cholinergic urticaria (CholU) is a common subtype of chronic inducible urticaria, where signs and symptoms (e.g. pruritic wheals and angioedema) are triggered by sweating due to physical exercise, passive warming and by other sweat-inducing situations. While guidelines recommend treatment with second-generation H1 antihistamines, approximately 90% of patients report uncontrolled disease. Targeting the histamine 4 receptor (H4R) has shown promise in preclinical/clinical studies of allergic/inflammatory diseases. Izuforant (LEO 152020) is a selective oral H4R antagonist with expected dual antipruritic and anti-inflammatory effects. OBJECTIVES: To assess the effects of izuforant in adults with CholU, a common type of chronic urticaria driven by histamine and characterized by high skin levels of H4R expression. METHODS: This was a phase IIa randomized double-blind placebo-controlled multicentre crossover trial where patients with CholU with an inadequate response to ≥ 1 standard dose of H1 antihistamine received izuforant 100 mg twice daily or placebo (EUCTR2020-004961-38-DE; NCT04853992). The primary endpoint was change from baseline in Urticaria Activity Score. Exploratory endpoints included CholU activity score over 7 days, urticaria control test, Physician Global Assessment, patient global assessment of severity (PGA-S), provocation tests, Dermatology Life Quality Index and CholU quality of life (CholU-QoL). Pharmacokinetic and pharmacodynamic parameters, and serum biomarkers were assessed, as well as safety and tolerability. RESULTS: Nineteen patients were randomized and included in the full analysis set; 18 completed treatment [mean (SD) age 29.5 (9.8) years; mean (SD) CholU duration 8.0 (6.3) years]. The primary and most of prespecified exploratory endpoints were not met; there were significant improvements in PGA-S for izuforant vs. placebo (P = 0.02), and nonsignificant improvements for other endpoints in quality of life and histamine skin prick test. All adverse events (AEs) experienced with izuforant were considered mild. The most frequently reported (> 1 patient) were nausea (three patients) and upper abdominal pain (two patients), occurring more frequently with izuforant vs. placebo (one patient each). There were no treatment-related serious AEs and no patient receiving izuforant discontinued the study. Treatment with izuforant did not cause downregulation of H4R. CONCLUSIONS: This is the first study to explore the role of H4R as a therapeutic target in urticaria. Targeting H4R with izuforant was well tolerated but did not demonstrate significant improvements vs. placebo in the primary endpoint and all but one prespecified exploratory endpoint in CholU.

Cholinergic urticaria (CholU) is a common subtype of an inflammatory skin condition called chronic inducible urticaria, where signs and symptoms (e.g. hives and swelling in the skin) are triggered by sweating caused by physical exercise, passive warming and other sweat-inducing situations. While guidelines recommend treatment with second-generation H1 antihistamines (a type of medication), approximately 90% of people with the condition report that these medications do not control the disease. Targeting the histamine 4 receptor (H4R) has shown promise in studies of allergic/inflammatory diseases. CholU is driven by histamine (a chemical released in the body) and characterized by high skin levels of H4R. Izuforant is a medication that may reduce itch and inflammation. In our study, which was carried out across multiple sites in Germany, we assessed the effects of izuforant 100 mg in 18 patients with CholU using a range of measures covering symptom control, disease severity, provocation response and quality of life. The primary endpoint (the main result measured at the end of the study to see if the treatment worked) was change from baseline in the post-provocation Urticaria Activity Score, where areas of skin were provoked and the time until common symptoms of CholU appeared (sweating and whealing (hives)) was measured. Overall, the primary endpoint and most of the exploratory endpoints were not met. There were significant improvements in patients' global assessment for izuforant versus placebo. This was the first study to explore the role of H4R as a therapeutic target in urticaria. Our findings suggest that targeting H4R with izuforant was well tolerated but did not demonstrate significant improvements versus placebo in the primary endpoint, and all but one prespecified exploratory endpoint in CholU.

Allergy to PEG (polyethylene glycol) - sensitivity of basophil activation test with COVID-19 mRNA-vaccine BNT162B2.

Basophil activation test (BAT) with COVID-19 mRNA vaccine seems particularly suitable for detecting sensitization to polyethylene glycol (PEG) in patients with PEG allergy. It was the aim of this study to determine the cutoffs for BAT using BNT162B2 (Comirnaty®) in a larger group of PEG allergic patients and controls. 10 PEG allergic patients and 10 controls were studied. BAT was performed using anti-CCR3 for basophil identification and anti-CD63 to assess basophil activation. Incubations with BNT162B2 at four different concentrations were performed. Basophil activation was significantly higher in PEG allergic patients compared to controls at the higher concentrations used. ROC curves showed best results with a sensitivity of 60% and specificity of 100% with a cutoff of 5% CD63+ basophils at a concentration of 4.5 µg/ml. Controls showed no positive results. In our group of PEG allergic patients, a concentration of 4.5 µg/ml BNT162B2 with a cutoff of 5% CD63+ basophils was the most suitable condition for identifying patients with a sensitization to PEG. Allergological work-up of PEG allergic patients including BAT with PEGylated lipid nanoparticles might play a role in the future when these substances will be used for other vaccines and cancer immunotherapies.

Challenges in the Diagnosis of Cutaneous Mastocytosis.

BACKGROUND: Mastocytosis is characterized by an accumulation of clonal mast cells (MCs) in tissues such as the skin. Skin lesions in mastocytosis may be clinically subtle or heterogeneous, and giving the correct diagnosis can be difficult. METHODS: This study compiles personal experiences together with relevant literature, discussing possible obstacles encountered in diagnosing skin involvement in mastocytosis and cutaneous mastocytosis (CM). RESULTS: The nomenclature of the term "CM" is ambiguous. The WHO classification defines CM as mastocytosis solely present in the skin. However, the term is also used as a morphological description, e.g., in maculopapular cutaneous mastocytosis (MPCM). This is often seen in systemic, as well as cutaneous, mastocytosis. Typical CM manifestations (MPCM), including mastocytoma or diffuse cutaneous mastocytosis (DCM), all share a positive Darier's sign, and can thus be clinically recognized. Nevertheless, distinguishing monomorphic versus polymorphic MPCM may be challenging, even for experienced dermatologists. Less typical clinical presentations, such as MPCM with telangiectatic erythemas (formerly called telangiectasia macularis eruptiva perstans), confluent, nodular or xanthelasmoid variants may require a skin biopsy for histopathological confirmation. Because MC numbers in CM have a large overlap to those in healthy and inflamed skin, detailed histopathological criteria to diagnose mastocytosis in MPCM are needed and have been proposed. D816V KIT mutational analysis in tissue is helpful for confirming the diagnosis. Biomarkers allow the prediction of the course of CM into regression or evolution of the disease. Further diagnostic measures should screen for concomitant diseases, such as malignant melanoma, and for systemic involvement. CONCLUSIONS: Whereas in typical cases the diagnosis of CM may be uncomplicated, less typical manifestations may require specific investigations for making the diagnosis and predicting its course.

Hypersensitivity reactions to proton pump inhibitors. An EAACI position paper.

Proton pump inhibitors (PPIs) are invaluable therapeutic options in a variety of dyspeptic diseases. In addition to their well-known risk profile, PPI consumption is related to food and environmental allergies, dysbiosis, osteoporosis, as well as immediate and delayed hypersensitivity reactions (HSRs). The latter, although a rare event, around 1%-3%, due to the extraordinarily high rate of prescription and consumption of PPIs are related to a substantial risk. In this Position Paper, we provide clinicians with practical evidence-based recommendations for the diagnosis and management of HSRs to PPIs. Furthermore, the unmet needs proposed in the document aim to stimulate more in-depth investigations in the topic.

EAACI/ENDA position paper on drug provocation testing.

In drug hypersensitivity, drug provocation testing (DPT), also called drug challenge, is the gold standard for investigation. In recent years, risk stratification has become an important tool for adjusting the diagnostic strategy to the perceived risk, whilst still maintaining a high level of safety for the patient. Skin tests are recommended before DPT but may be omitted in low-risk patients. The task force suggests a strict definition of such low-risk patients in children and adults. Based on experience and evidence from studies of allergy to beta-lactam antibiotics, an algorithm on how to adjust DPT to the risk, and when to omit skin tests before DPT, is presented. For other antibiotics, non-steroidal anti-inflammatory drugs and other drugs, skin tests are poorly validated and DPT is frequently necessary. We recommend performing DPT with chemotherapeutics and biologicals to avoid unnecessary desensitization procedures and DPT with skin tests negative contrast media. We suggest DPT with anesthetics only in highly specialized centers. Specifics of DPT to proton pump inhibitors, anticonvulsants and corticosteroids are discussed. This position paper provides general recommendations and guidance on optimizing use of DPT, whilst balancing benefits with patient safety and optimizing the use of the limited available resources.

Declining frequency of sensitization to fragrance mixes I and II: IVDK-data of the years 2012-2021.

BACKGROUND: EU Commission Regulation 2017/1410 prohibits using atranol and chloroatranol, the main allergens in Evernia prunastri (oakmoss), and hydroxyisohexyl 3-cyclohexene carboxaldehyde (HICC) in cosmetic products. Oakmoss absolute is contained in fragrance mix (FM) I and HICC in FM II which are patch tested as screening mixtures in the baseline series. OBJECTIVE: To describe the time trends of reaction frequencies to both FMs as well as to their components in FM-positive patients. METHODS: Retrospective analysis of data from the Information Network of Departments of Dermatology (IVDK), 2012-2021. RESULTS: Positive reactions to FM I (FM II) declined from 9.1% (4.7%) in 2012 to 4.6% (3.0%) in 2021. Full breakdown tests were performed in 24% (FM I) and 31% (FM II), respectively, of the mix-positive patients. From this data, frequencies of sensitization to the 14 single fragrances of FM I and FM II were calculated. For the majority, a decline was noted from 2012/2013 to 2020/2021, for oakmoss absolute 1.9%-0.8% and for HICC 1.8%-0.9%. CONCLUSION: EU Commission Regulation 2017/1410 was an effective measure. However, our data have some limitations, possibly causing underestimation of sensitization frequencies to fragrances.