Pathogenesis and diagnosis of delayed-type drug hypersensitivity reactions, from bedside to bench and back

DRESS Syndrome: Renal Involvement in Two Cases - A Comprehensive Analysis and Literature Review of Improved Diagnosis and Treatment

BACKGROUND Drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome is a rare hypersensitivity reaction involving the skin and various visceral organs; the kidneys are the second most affected organ. Many drugs are reported to be associated with DRESS, particularly antiepileptic agents and allopurinol. Certain human leukocyte antigen (HLA) haplotypes, in combination with a particular drug, can further contribute to an increased risk of DRESS. Symptoms often develop 2 to 8 weeks after drug initiation. If diagnosis is delayed, DRESS can be a life-threatening condition. CASE REPORT We present cases of 2 patients. The first patient was an 86-year-old Polish woman who developed acute kidney injury and skin lesions with accompanying leucocytosis and eosinophilia during long-term antibiotic therapy with piperacillin/tazobactam and ciprofloxacin. The second patient was a 37-year-old Asian woman with predialysis chronic renal disease stage V in the course of IgA nephropathy. Two weeks after starting allopurinol in a standard dose, she presented with maculopapular rash, facial edema, fever, liver injury, and eosinophilia. Renal function started to deteriorate, but she did not require dialysis. In both cases, the discontinuation of the above-mentioned drugs and the introduction of steroid therapy and intravenous immunoglobulins allowed for clinical improvement and recovery. In the second case, the extended 4-locus HLA typing was performed retrospectively, and allele HLA-B*5801 was found. CONCLUSIONS Due to the rare occurrence and heterogeneous manifestation of DRESS, its diagnosis can pose many difficulties. In-depth analysis of symptoms, medicines taken, and laboratory findings enable the implementation of appropriate treatment and recovery.

Cyanoacrylate glue reactions: A systematic review, cases, and proposed mechanisms

OBJECTIVE

Cyanoacrylate glue closure was first used in humans 10 years ago to treat venous reflux of the axial veins. Studies have since shown its clinical efficacy in vein closure. However, great need exists to elucidate further the types of specific adverse reactions that cyanoacrylate glue can cause for better patient selection and to minimize these events. In the present study, we systematically reviewed the literature to identify the types of reported reactions. In addition, we explored the pathophysiology contributing to these reactions and proposed the mechanistic pathway with inclusion of actual cases.

METHODS

We searched the literature for reports of reactions following cyanoacrylate glue use in patients with venous diseases between 2012 and 2022. The search was performed using MeSH (medical subject headings) terms. The terms included cyanoacrylate, venous insufficiency, chronic venous disorder, varicose veins, vein varicosities, venous ulcer, venous wound, CEAP (clinical, etiologic, anatomic, pathophysiologic), vein, adverse events, phlebitis, hypersensitivity, foreign body granuloma, giant cell, endovenous glue-induced thrombosis, and allergy. The search was limited to the literature reported in English. These studies were evaluated for the type of product used and the reactions noted. A systematic review, in accordance with the PRISMA (preferred reporting items for systematic reviews and meta-analyses) method, was performed. Covidence software (Melbourne, VC, Australia) was used for full-text screening and data extraction. Two reviewers reviewed the data, and the content expert served as the tiebreaker.

RESULTS

We identified 102, of which, 37 reported on cyanoacrylate use other than in the context of chronic venous diseases and were excluded. Fifty-five reports were determined appropriate for data extraction. The adverse reactions to cyanoacrylate glue were phlebitis, hypersensitivity, foreign body granuloma, and endovenous glue-induced thrombosis.

CONCLUSIONS

Although cyanoacrylate glue closure for venous reflux is generally a safe and clinically effective treatment choice for patients with symptomatic chronic venous disease and axial reflux, some adverse events could be specific to the properties of the cyanoacrylate product. We propose mechanisms for how such reactions can occur based on histologic changes, published reports, and case examples; however, further exploration is necessary to confirm these theories.

Drug-Induced Enterocolitis Syndrome in Children

Drug-Induced Enterocolitis Syndrome (DIES) is a drug-induced hypersensitivity reaction non-IgE mediated involving the gastrointestinal system that occurs 2 to 4 h after drug administration. Antibiotics, specifically amoxicillin or amoxicillin/clavulanate, represent the most frequent drugs involved. Symptoms include nausea, vomiting, abdominal pain, diarrhea, pallor, lethargy, and dehydration, which can be severe and result in hypovolemic shock. The main laboratory finding is neutrophilic leukocytosis. To the best of our knowledge, 12 cases of DIES (9 children-onset and 3 adult-onset cases) were described in the literature. DIES is a rare clinically well-described allergic disease; however, the pathogenetic mechanism is still unclear. It requires to be recognized early and correctly treated by physicians.

A Case of Vancomycin-Induced Drug Reaction with Eosinophilia, Systemic Symptoms and Multiorgan Involvement Proven Using Lymphocyte Transformation Test

Drug-induced hypersensitivity syndrome (DiHS), also referred to as drug reaction with eosinophilia and systemic symptoms (DRESS), is a rare but potentially life-threatening condition induced by drug hypersensitivity that leads to significant morbidity and mortality and often occurs in patients undergoing combination antibiotic therapy. Due to a recent increase in the incidence of methicillin-resistant Staphylococcus aureus infections, the occurrence of vancomycin-induced DiHS/DRESS has increased rapidly. However, because of insufficient pharmacogenetic data on vancomycin-induced drug eruptions in Asians coupled with the risk of re-eliciting the symptoms by provocation tests, confirmation of the culprit drug in vancomycin-induced DiHS/DRESS is often challenging. Here, we report a case of vancomycin-induced DiHS/DRESS, where the causal relationship was confirmed using a lymphocyte transformation test (LTT). A 51-year-old woman was treated with combination antibiotics, including vancomycin, for infective pericarditis. The patient subsequently developed fever, facial edema, generalized rash followed by multiple internal organ involvement, including the kidney, lung, liver, and heart. Thus, based on the International Registry of Severe Cutaneous Adverse Reaction (RegiSCAR) criteria, the case was diagnosed as 'definite' DiHS/DRESS, although the culprit drug was obscured by combination antibiotic therapy. The LTT confirmed that vancomycin, but not other glycopeptide antibiotics, specifically induced T-cell proliferation in this case. Collectively, our case suggests that clinicians can utilize LTT to identify the causative medication of DiHS/DRESS when the clinical information is limited to defining the culprit drug.

Conjugation of human serum albumin and flucloxacillin provokes specific immune response in HLA-B*57:01 transgenic mice

Flucloxacillin (FLX) induces adverse liver reactions, which has been reported to be related to human leukocyte antigen (HLA)-B*57:01. In a previous study, abacavir-induced hypersensitivity was induced in HLA-B*57:01-transgenic mice (B*57:01-Tg), originally constructed by our group (Susukida et al., 2021). In this study, B*57:01-Tg mice were used to reproduce FLX-induced liver injury. However, treatment of B*57:01-Tg mice with FLX alone did not increase serum ALT levels. Immune-deficient B*57:01-Tg/PD-1^-/-mice were produced by mating B*57:01-Tg with PD-1^-/- mice. The immune response of B*57:01-Tg/PD-1^-/- mice was further modulated by co-administration of CpG-oligodeoxynucleotides and anti-CD4 mAb. Nevertheless, immune regulation in B*57:01-Tg mice did not contribute to the onset of FLX-induced liver injury or immune activation. Moreover, we generated an FLX-human serum albumin (HSA) conjugate and showed that FLX covalently bound to HSA in a time-dependent manner. The FLX-HSA conjugate was administered to the B*57:01-Tg mice. The immune response was investigated using flow cytometry, revealing the phenotype of CD44^highCD62L^low in CD8⁺ T cells (T_EM cells). Administration of the FLX-HSA conjugate resulted in an HLA-B*57:01 restricted immune response as shown by the stimulation of T_EM cells in the draining lymph nodes. In conclusion, administration of FLX alone to B*57:01-Tg mice did not induce liver injury or immune activation. Immune system sensitivity does not play a decisive role in this process. The conjugation of FLX and HSA results in specific T_EM cell stimulation, which suggests that HLA-B*57:01 drives a stronger interaction with CD8⁺ T cells. These results suggest that patients carrying HLA-B*57:01 could be more susceptible to a conjugate of FLX and albumin and drive CD8⁺ T cell activation, which may be a vital risk factor for FLX-induced liver injury. In addition, the application of the FLX-HSA adduct may be an effective method for the construction of FLX-induced idiosyncratic liver injury in mice.

Pathology of T-cell-mediated drug hypersensitivity reactions and impact of tolerance mechanisms on patient susceptibility

PURPOSE OF REVIEW

T-cell-mediated drug hypersensitivity is responsible for significant morbidity and mortality, and represents a substantial clinical concern. The purpose of this article is to focus on T-cell reactions and discuss recent advances in disease pathogenesis by exploring the impact of tolerance mechanisms in determining susceptibility in genetically predisposed patients.

RECENT FINDINGS

Certain drugs preferentially activate pathogenic T cells that have defined pathways of effector function. Thus, a critical question is what extenuating factors influence the direction of immune activation. A large effort has been given towards identifying phenotypic (e.g., infection) or genotypic (e.g., human leukocyte antigen) associations which predispose individuals to drug hypersensitivity. However, many individuals expressing known risk factors safely tolerate drug administration. Thus, mechanistic insight is needed to determine what confers this tolerance. Herein, we discuss recent clinical/mechanistic findings which indicate that the direction in which the immune system is driven relies upon a complex interplay between co-stimulatory/co-regulatory pathways which themselves depend upon environmental inputs from the innate immune system.

SUMMARY

It is becoming increasingly apparent that tolerance mechanisms impact on susceptibility to drug hypersensitivity. As the field moves forward it will be interesting to discover whether active tolerance is the primary response to drug exposure, with genetic factors such as HLA acting as a sliding scale, influencing the degree of regulation required to prevent clinical reactions in patients.

Inherent clinical properties of non-immediate hypersensitivity to iodinated contrast media

BACKGROUND

Iodinated contrast media (ICM) is a frequently used compound in radiology. Non-immediate hypersensitivity reactions (HSR) appear when a patient leaves the department and usually are undocumented. True hypersensitivity in this group is rarely proved.

METHODS

Single-centre 2014-2018 data were retrospectively analysed. HSR to ICM were classified and investigated according to the time of occurrence (immediate <1 hour, non-immediate >1 hour). ENDA questionnaire and skin tests (prick or intradermal test) were performed according to ENDA/EAACI recommendations.

RESULTS

69 patients with a clinical history of HSR to ICM were identified, 72.46% were females (n = 50). The average age was 56 (SD ± 13.16) years. Non-immediate HSR occurred in 28.99% (n = 20) patients. The suspected culprit drugs were: iodixanol 20% (n = 4), iopromide 5% (n = 1), diatrizoate 10% (n = 2) and iohexol 10% (n = 2). Among non-immediate HSR 96.00% (n = 19) of patients had skin rashes. A statistically significant correlation was found between the clinical symptoms and the type of reaction (p-value <0.05): isolated skin manifestations mostly occurred in non-immediate HSR 75.00% (n = 15). Only 13.04% (n = 9) of all the patients were proved to be allergic to a certain ICM after the proposed diagnostic workup.

CONCLUSIONS

One-third of the hypersensitivity reactions investigated were classified as non-immediate type. Most of them manifested with isolated skin symptoms. The most frequent culprit drug encountered was iodixanol. The overall non-immediate hypersensitivity confirmation rate after diagnostic evaluation was only 15%.

Lymphocyte transformation test and cytokine detection assays: Determination of read out parameters for delayed-type drug hypersensitivity reactions

Drug hypersensitivity reactions (DHRs) occur in certain people and are often not predictable. DHRs can be classified as immediate and delayed reactions regarding to onset of clinical manifestations. Both reactions are considered to be an important public health problem because they can lead to life-threatening conditions; however, this review article will focus on delayed DHRs. The most important points for diagnosis of delayed DHRs are the recognition of drug hypersensitivity characteristics and culprit drug identification. While it is usually difficult to identify a culprit drug; clinical evaluation using the causality assessment method, a non-invasive process, can identify the culprit drug without the need for intensive investigation. Delayed DHRs can cause life-threatening conditions; therefore, in vivo skin tests, as well as drug provocation tests, have to be cautiously performed by a drug allergist and have not been recommended in uncontrolled conditions. ENDA/EAACI has recommended that in vitro tests (if available) be performed prior to any in vivo tests. Therefore, in vitro diagnostic tests can be alternative methods to identify a culprit drug for delayed DHR diagnosis as there is no or very low risk for patients under investigation. There are many testing approaches to identify causative agents for delayed DHRs such as: the lymphocyte transformation test (LTT), cytokine/mediator detection assays (i.e. ELISA and flow cytometry-based bead assays), multiplex bead-based immunoassay and ELISpot. The LTT is the most standardized method whereas it has been available in medical schools affiliated with university hospitals. Other in vitro tests, like cytokine detection assays, have also been used, even though they are still being evaluated. They could supplement LTT results that would provide drug allergist's with documentary evidence and prevent risk to patients by avoiding in vivo or drug provocation testing. Hence, the in vitro tests have been promising tests contributing to the management of the delayed DHR work-up process in clinical practice.

Eosinophils in skin diseases

Eosinophil infiltration is a common finding in a broad spectrum of skin diseases, despite the fact that the skin is devoid of eosinophils under physiologic conditions. Although cutaneous eosinophilia is reactive, cytokine-mediated in most cases, diseases with an intrinsic mutation-mediated clonal expansion of eosinophils can also manifest on the skin. As eosinophils are involved in host defense, regulate immune responses, generate pruritus, induce remodeling and fibrosis, and can cause tissue damage, they have the capacity to actively contribute to the pathogenesis of diseases. Recent research provided deeper insights in the mechanisms, e.g., bacterial and viral clearance, blister formation, recruitment of cytotoxic T cells, and generation of pruritus, by which eosinophils might come into action. This review aims at providing an overview on the clinical presentations of eosinophil-associated dermatoses and the current understanding of their pathogenic role in these diseases. Further, we discuss the effects of therapies targeting eosinophils.

HLA-B*13 :01 Is a Predictive Marker of Dapsone-Induced Severe Cutaneous Adverse Reactions in Thai Patients

HLA-B*13:01 allele has been identified as the genetic determinant of dapsone hypersensitivity syndrome (DHS) among leprosy and non-leprosy patients in several studies. Dapsone hydroxylamine (DDS-NHOH), an active metabolite of dapsone, has been believed to be responsible for DHS. However, studies have not highlighted the importance of other genetic polymorphisms in dapsone-induced severe cutaneous adverse reactions (SCAR). We investigated the association of HLA alleles and cytochrome P450 (CYP) alleles with dapsone-induced SCAR in Thai non-leprosy patients. A prospective cohort study, 16 Thai patients of dapsone-induced SCARs (5 SJS-TEN and 11 DRESS) and 9 Taiwanese patients of dapsone-induced SCARs (2 SJS-TEN and 7 DRESS), 40 dapsone-tolerant controls, and 470 general Thai population were enrolled. HLA class I and II alleles were genotyped using polymerase chain reaction-sequence specific oligonucleotides (PCR-SSOs). CYP2C9, CYP2C19, and CYP3A4 genotypes were determined by the TaqMan real-time PCR assay. We performed computational analyses of dapsone and DDS-NHOH interacting with HLA-B*13:01 and HLA-B*13:02 alleles by the molecular docking approach. Among all the HLA alleles, only HLA-B*13:01 allele was found to be significantly associated with dapsone-induced SCARs (OR = 39.00, 95% CI = 7.67–198.21, p = 5.3447 × 10⁻⁷), SJS-TEN (OR = 36.00, 95% CI = 3.19–405.89, p = 2.1657 × 10⁻³), and DRESS (OR = 40.50, 95% CI = 6.38–257.03, p = 1.0784 × 10⁻⁵) as compared to dapsone-tolerant controls. Also, HLA-B*13:01 allele was strongly associated with dapsone-induced SCARs in Asians (OR = 36.00, 95% CI = 8.67–149.52, p = 2.8068 × 10⁻⁷) and Taiwanese (OR = 31.50, 95% CI = 4.80–206.56, p = 2.5519 × 10⁻³). Furthermore, dapsone and DDS-NHOH fit within the extra-deep sub pocket of the antigen-binding site of the HLA-B*13:01 allele and change the antigen-recognition site. However, there was no significant association between genetic polymorphism of cytochrome P450 (CYP2C9, CYP2C19, and CYP3A4) and dapsone-induced SCARs (SJS-TEN and DRESS). The results of this study support the specific genotyping of the HLA-B*13:01 allele to avoid dapsone-induced SCARs including SJS-TEN and DRESS before initiating dapsone therapy in the Asian population.

Lymphocyte transformation test: History and current approaches

Drug-induced hypersensitivity reactions encompass a variety of different clinical phenotypes ranging from harmless rashes to fatal reactions. They can be classified into allergic (i.e. drug allergy) and non-allergic reactions (i.e. non-allergic hypersensitivity). Drug allergies in turn can either be antibody (e.g. IgE) or T cell-mediated. One of the diagnostic tools for the in vitro detection of drug allergy is the lymphocyte transformation test (LTT) which is based on the activation and expansion of the drug-specific memory T cells following co-incubation of the patient's peripheral mononuclear cells (PMBC) with the suspected drug in vitro. The read-out parameter in the classical LTT is T cell proliferation which can be measured as counts per minute following the addition of radiolabeled thymidine to the cell culture. However, in the course of time different modifications of the classical LTT with regard to the read-out parameters and methods have been proposed. Likewise, variations of the LTT platform itself have been described in the literature. This review article describes the development of the classical LTT and its use in the context of drug allergy detection and summarizes the modifications which have been published over time.

Drug hapten-specific T-cell activation: Current status and unanswered questions

Drug haptens are formed from the irreversible, covalent binding of drugs to nucleophilic moieties on proteins, which can warrant adverse reactions in the body including severe delayed-type, T-cell mediated, drug hypersensitivity reactions (DHRs). While three main pathways exist for the activation of T-cells in DHRs, namely the hapten model, the pharmacological interaction model and the altered peptide repertoire model, the exact antigenic determinants responsible have not yet been defined. In recent years, progress has been made using advanced mass spectrometry-based proteomic methods to identify protein carriers and characterise the structure of drug-haptenated proteins. Since genome-wide association studies discovered a link between human leukocyte antigens (HLA) and an individual's susceptibility to DHRs, much effort has been made to define the drug-associated HLA ligands driving T-cell activation, including the elution of natural HLA peptides from HLA molecules and the generation of HLA-binding peptides. In this review, we discuss our current methodology used to design and synthesise drug-modified HLA ligands to investigate their immunogenicity using T-cell models, and thus their implication in drug hypersensitivity.

Advances and novel developments in drug hypersensitivity diagnosis

A correct diagnosis of drug hypersensitivity reactions (DHRs) is very important for both the patient and health system. However, DHRs diagnosis is complex, time consuming, requires trained personnel, is not standardized for many drugs, involves procedures not exempt of risk, and in most cases lacks standardized in vivo and in vitro tests. Thus, there is an urgent need for improving the different approaches to diagnose patients with suspected DHRs. In this review, we have analyzed the advances performed in immediate and nonimmediate DHRs diagnosis during the last two years and obtained several conclusions: the significant heterogeneity in current practice among centers illustrates the need to re-evaluate, update, and standardize in vivo tests and protocols for the diagnosis and management of patients with suspected drug allergy. Regarding in vitro tests, the latest studies have focused on increasing their sensitivity or on establishing the sensitivity and specificity for the tests performed with new drugs. There seems to be a consensus about combining in vivo and in vitro tests as the best way to increase the diagnostic accuracy.

Clinical value of in vitro tests for the management of severe drug hypersensitivity reactions

Drug hypersensitivity reactions (DHRs) occasionally present with severe cutaneous adverse reactions (SCARs) which result in a high risk of morbidity and mortality. Although SCARs are rare, the occurrence could lead to a significant increase in healthcare and economic burden, especially when more than one possible culprit drug is implicated. Therefore, the accurate identification of the culprit drug(s) is important for correct labeling and subsequent patient education and avoidance. To date, clinical evaluation using causality assessment has limitations because the assessment may be inaccurate due to the overlapping timelines when multiple drugs are initiated/continued. Moreover, drug provocation tests (DPTs) which is the gold standard in diagnosis, are contraindicated, and in vivo skin tests may also be associated with risks of triggering SCAR. The European Network for Drug Allergy recommended that in vitro tests, if available, should be performed before any in vivo tests. Basophil activation tests and lymphocyte transformation tests, could serve as reliable in vitro tests for both immediate and delayed-type DHR. Many academic medical centers with affiliated laboratory services offer these tests in the diagnostic evaluation of SCARs in clinical practice. This not only complements identification of the culprit drug(s), but may also be used to test for potentially non cross-reactive alternatives, hence avoiding DPTs. In this review, we summarize the roles of in vitro tests in identifying the culprit drug(s) in SCARs, issues with utilization and interpretation of test results, and our experience in clinical practice.

A Survey on Knowledge Gaps in Assessment and Management of Severe Drug Hypersensitivity Reactions: Multicenter Cross-Sectional Study of Australian Health Care Providers

Severe drug hypersensitivity reactions (DHRs) are often encountered by health care professionals (HCPs). We evaluated knowledge of doctors and pharmacists in the assessment and management of severe DHRs using a structured questionnaire. A cross-sectional study was conducted in 4 metropolitan hospital networks in Melbourne, Australia. A 13-question, scenario-based multiple-choice questionnaire to assess specific knowledge domains in drug hypersensitivity syndrome recognition, causality attribution, cross-reactivity patterns, appropriate diagnostic tests, and therapy was administered to HCPs of various vocation and specialty groups. Data were analyzed according to profession, self-reported experience, and preparedness in managing severe DHRs. Two hundred thirty-eight participants (45.0% senior doctors, 24.4% junior doctors, and 30.7% pharmacists) across a range of subspecialties achieved an overall median score of 7 (IQR, 5-8)-overall 55.6% correct responses to all questions-with senior doctors outperforming junior doctors and pharmacists (P < .001). The best performance by all participants was in DHR syndrome recognition (60.9%), and the poorest was in diagnostics/therapy (52.0%). HCP group and experience level were significantly associated with better performance in the knowledge domains of cross-reactivity and diagnostics/therapy (P = .003 and < .001, respectively), but not in the domains of syndrome recognition and causality attribution (P > .05). Levels of self-reported preparedness in DHR management were not associated with performance rates in any of the knowledge domains. This study demonstrated significant knowledge gaps in the recognition and management of severe drug hypersensitivity reactions. Targeted multidisciplinary education of staff caring for these patients is needed to improve knowledge gaps.

A Case of Alveolar Haemorrhage Induced by Iodinated Contrast Medium Use

An 81-year-old man complaining of exertional dyspnoea underwent coronary angiography using an iodinated contrast medium. After angiography, the patient required systemic corticosteroid therapy because of respiratory failure due to alveolar haemorrhage. Percutaneous coronary intervention was performed 29 days after angiography using the same contrast medium. After the intervention, the patient required intubated mechanical ventilation and renal replacement therapy. Bronchoalveolar lavage was bloody with many haemosiderin-filled macrophages. Systemic corticosteroid therapy again improved his clinical condition. Iodinated contrast media may cause alveolar haemorrhage and re-exposure to contrast media may induce a more severe adverse reaction.

LEARNING POINTS

Iodinated contrast media may cause alveolar haemorrhage.Re-exposure to iodinated contrast media may induce a more severe adverse reaction.

Bullous pemphigoid-like skin rash associated with Rivaroxaban use in a very elderly patient with multimorbidity and chronic kidney disease: A case report

Direct oral anticoagulants (DOACs) are increasingly being used in the elderly population in view of its ease of use, efficacy, and favorable side-effect profile compared with the vitamin K antagonists. However, there is a need for increase awareness of well-characterized cases, albeit a small number, of bullous pemphigoid-like skin reactions associated with rivaroxaban.

Epidemiology and drug allergy results in children investigated in allergy unit of a tertiary-care paediatric hospital setting

Background and objective

Drug Hypersensitivity Reactions (DHRs) are considered adverse effects of medications that resemble allergy symptoms. The reported positive clinical history of pediatric drug reactions is about 10%, however, after allergy investigations, only a small percent is confirmed as hypersensitivity.

The aim of this study was to analyze the clinical history, allergy work-up results and sensitization profile of children and adolescents referred to our Allergy Unit for suspected DHRs.

Methods

The study evaluated data related to a group of children with a positive history of drug reactions during a two-year period. The allergy work-up consisted of in vivo and in vitro tests, in accordance with the recommendations of the ENDA/EAACI guidelines.

Results

Data from a group of 637 patients [348 M (54.6%); 289 F (45.4%)] were retrospectively analyzed. Beta lactams (BLs) were the most common drugs involved in the reported clinical history, followed by non-steroidal anti-inflammatory drugs (NSAIDs). Severe cutaneous adverse reactions (SCARs) were most frequently observed during BL treatment. The confirmation of BL hypersensitivity was higher for immediate reactions (IRs) [9.4%; 5.1% through positive skin tests (STs) and 5.5% through drug provocation test (DPT)] compared to non-immediate reactions (non-IRs) (8.1%; 2.2% through STs and 6.2% through DPT). A higher number of positive results was obtained for BLs and macrolides when the tests were performed within 12 months after the index reaction (p < 0.05). During DPTs with amoxicillin-clavulanic acid, four hypersensitivity reactions (including one anaphylaxis) occurred despite negative STs.

Conclusion

Our data demonstrated that only 9.1% of patients resulted in being positive to allergy tests which is in line with the data in literature. An allergy work-up is mandatory for excluding suspected hypersensitivity.

Successful cholecalciferol desensitisation in a case of delayed hypersensitivity

Hypersensitivity to cholecalciferol (vitamin D₃) or its active metabolite, calcitriol, is an exceedingly rare clinical phenomenon, with only 2 previously reported cases of suspected immediate hypersensitivity. Diagnosis of delayed drug hypersensitivity reactions is inherently difficult due to the lack of any robust in vitro diagnostic assay, particularly in those patients for whom provocation testing confers an unacceptable risk. In these situations, diagnosis relies on reproducible clinical manifestations following administration of the culprit agent, resolution upon its withdrawal and exclusion of other potential differential diagnoses. Based on these criteria, we propose the first reported case of delayed hypersensitivity to cholecalciferol successfully managed with a desensitisation protocol to pure cholecalciferol.

Altered retinoid metabolism gene expression in chronic Stevens-Johnson syndrome

Background

Stevens-Johnson syndrome (SJS), a blistering disorder of the skin and mucous membrane, leads to ocular morbidity in >60% of cases. Retinoids are vital micronutrients for vision, regulating corneal and conjunctival cell proliferation, differentiation and immune function. This prospective case–control study probed for alterations in retinoid metabolism by evaluating retinoic acid receptor signalling in the conjunctival cells of patients with SJS.

Methods

Imprints were collected from the bulbar conjunctiva of patients with chronic SJS. The gene expression of retinoic acid receptors, namely, RXRA, RARA, RARG, RORA; the fibrosis marker TGFβ and its receptor TGFβRII; the transcription factors PPAR-γ, STRA6 and Stat3; the enzymes aldehyde dehydrogenase (ALDH1a1), alpha-1 antitrypsin (A1AT); and the Cyp genes Cyp26a1 and Cyp26b1 were assessed by quantitative PCR in patients with SJS pre-mucous (n = 34) and post-mucous membrane graft (MMG) intervention (n=19) in comparison with age-matched/sex-matched healthy controls (n=20). Western blot analysis of ALDH1a1, RARA and RARG were done in the conjunctival imprint cells.

Results

The transcript levels of ALDH1a1, RXRA, RORA, STRA6, Cyp26a1 and Cyp26b1 were decreased around 4, 26, 17, 129, 9 and 8 folds, respectively, and RARA, RARG, PPAR-γ, TGFβ, TGFβRII were increased by 12, 15, 51, 16 and 87 folds, respectively, in SJS conjunctiva at the pre-MMG stage. The changes in RORA, Cyp26a1, Cyp26b1, RARA and Stat3 were statistically significant (p<0.05). Changes in protein expression of ALDH1a1, RARA and RARG supported the gene expression changes.

Conclusions

The study provides the first experimental insight into the role of retinoid metabolism in the ocular sequelae of chronic SJS.

Bullous Pemphigoid with Atypical Skin Lesions and Acute Interstitial Nephritis: A Case Report and Focused Literature Review

Patient: Male, 76

Final Diagnosis: Drug induced bullous pemphigoid

Symptoms: Skin rash

Medication: Cephalexin

Clinical Procedure: Skin biopsy

Specialty: General and Internal Medicine

Drug-Induced Skin Adverse Reactions: The Role of Pharmacogenomics in Their Prevention

Adverse drug reactions (ADRs) affect many patients and remain a major public health problem, as they are a common cause of morbidity and mortality. It is estimated that ADRs are responsible for about 6% of hospital admissions and about 9% of hospitalization costs. Skin is the organ that is most frequently involved in ADRs. Drug-induced skin injuries vary from mild maculopapular eruptions (MPE) to severe cutaneous adverse reactions (SCARs) that are potentially life threatening. Genetic factors have been suggested to contribute to these SCARs, and most significant genetic associations have been identified in the major histocompatibility complex (MHC) genes. Common drugs associated with SCARs connected with strong genetic risk factors include antiepileptic drugs (AEDs), allopurinol, abacavir, nevirapine, sulfonamides, dapsone, non-steroidal anti-inflammatory drugs (NSAIDs), and analgesic drugs. However, genetic associations vary between different ethnic populations. Differences may in part be explained by the different prevalence of HLA (human leukocyte antigen) alleles among ethnic groups. In this review, we present and discuss the recent advances in genetic associations with ADRs in the skin. Many of these ADRs are now preventable with pharmacogenetic screening.

Piperacillin-Tazobactam-Induced Linear IgA Bullous Dermatosis Supported by a T-Cell Activation Assay

Linear immunoglobulin (Ig) A bullous dermatosis (LABD) is a rare subepidermal autoimmune blistering disease characterized by linear IgA deposits at the basement membrane zone visualized with direct immunofluorescence (DIF). Most cases of LABD are idiopathic, but some are drug-induced with vancomycin being the most common causative agent. We herein report a patient presenting with blisters and erosive lesions, primarily in the intertriginous and flexor areas, consistent with a diagnosis of piperacillin-tazobactam-induced LABD based on the patient's clinical course and histopathology, DIF, and in vitro T-cell activation assay (TAA) findings. Only one case of piperacillin-tazobactam-induced LABD has been previously reported. In addition to its rarity, our case was also unique in that the skin lesions occurred in the intertriginous and flexor areas, uncommon locations for typical adult patients with LABD, and TAA strongly suggested an association with the causative drug.

Accumulation of CD69+ tissue‑resident memory T cells in the nasal polyps of patients with chronic rhinosinusitis

In patients with chronic rhinosinusitis with nasal polyps (CRSwNP), a relative accumulation of cluster of differentiation (CD)8+ T cells over CD4+ T cells occurs in nasal polyps compared with the peripheral blood. Nasal CD8+ T cells and CD4+ T cells predominantly present an effector memory phenotype. Immunological studies have reported that memory T cells recirculate from the tissues to the peripheral blood and a high percentage of these T cells persist within the tissue. The aim of the present study was to characterize CD69+ sphingosine‑1‑phosphate receptor 1 (S1PR1)‑ tissue resident memory T cells (Trm) in the polyps of patients with CRSwNP. Tissue and blood samples were collected from 10 patients undergoing nasal sinus surgery. Expression of specific extra‑ and intracellular molecules were analyzed using multicolor flow cytometry. A significantly higher level of CD8+ T cells than CD4+ T cells was present in nasal polyps, while significantly more CD4+ T cells than CD8+ T cells were detected in the peripheral blood of patients with CRSwNP. The frequency of CD69+ T cells was significantly higher in CD8+ and CD4+ T cells in nasal polyps compared with the peripheral blood. The frequency of CD69+ S1PR1‑ Trm was also significantly higher in CD4+ and CD8+ T cells from nasal polyps compared with the peripheral blood. Within polyps, the frequency of CD69+ S1PR1‑ Trm was again significantly higher in CD8+ compared with CD4+ T cells. In summary, a significantly higher frequency of CD69+ S1PR1‑ T cells was observed in the nasal polyps compared with the peripheral blood in patients with CRSwNP. The results of the present study suggest that local regulation of the immune response occurs within nasal polyps. As such, Trm should be considered a potential stimulus in the pathogenesis of nasal polyps. However, the role of Trm in nasal polyps as a pathogenic trigger of the local inflammatory reaction requires further investigation.

Drug-Induced Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis Call for Optimum Patient Stratification and Theranostics via Pharmacogenomics

The Global Genomic Medicine Collaborative, a multinational coalition of genomic and policy experts working to implement genomics in clinical care, considers pharmacogenomics to be among the first areas in genomic medicine that can provide guidance in routine clinical practice, by linking genetic variation and drug response. Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are severe life-threatening reactions to medications with a high incidence worldwide. Genomic screening prior to drug administration is a key opportunity and potential paradigm for using genomic medicine to reduce morbidity and mortality and ultimately eliminate one of the most devastating adverse drug reactions. This review focuses on the current understanding of the surveillance, pathogenesis, and treatment of SJS/TEN, including the role of genomics and pharmacogenomics in the etiology, treatment, and eradication of preventable causes of drug-induced SJS/TEN. Gaps, unmet needs, and priorities for future research have been identified for the optimal management of drug-induced SJS/TEN in various ethnic populations. Pharmacogenomics holds great promise for optimal patient stratification and theranostics, yet its clinical implementation needs to be cost-effective and sustainable.

Randomized, controlled trial of TNF-α antagonist in CTL-mediated severe cutaneous adverse reactions

BACKGROUND

Cytotoxic T lymphocyte-mediated (CTL-mediated) severe cutaneous adverse reactions (SCARs), including Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN), are rare but life-threatening adverse reactions commonly induced by drugs. Although high levels of CTL-associated cytokines, chemokines, or cytotoxic proteins, including TNF-α and granulysin, were observed in SJS-TEN patients in recent studies, the optimal treatment for these diseases remains controversial. We aimed to evaluate the efficacy, safety, and therapeutic mechanism of a TNF-α antagonist in CTL-mediated SCARs.

METHODS

We enrolled 96 patients with SJS-TEN in a randomized trial to compare the effects of the TNF-α antagonist etanercept versus traditional corticosteroids.

RESULTS

Etanercept improved clinical outcomes in patients with SJS-TEN. Etanercept decreased the SCORTEN-based predicted mortality rate (predicted and observed rates, 17.7% and 8.3%, respectively). Compared with corticosteroids, etanercept further reduced the skin-healing time in moderate-to-severe SJS-TEN patients (median time for skin healing was 14 and 19 days for etanercept and corticosteroids, respectively; P = 0.010), with a lower incidence of gastrointestinal hemorrhage in all SJS-TEN patients (2.6% for etanercept and 18.2% for corticosteroids; P = 0.03). In the therapeutic mechanism study, etanercept decreased the TNF-α and granulysin secretions in blister fluids and plasma (45.7%-62.5% decrease after treatment; all P < 0.05) and increased the Treg population (2-fold percentage increase after treatment; P = 0.002), which was related to mortality in severe SJS-TEN.

CONCLUSIONS

The anti-TNF-α biologic agent etanercept serves as an effective alternative for the treatment of CTL-mediated SCARs.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01276314.

FUNDING

Ministry of Science and Technology of Taiwan.

Dapsone-induced severe cutaneous adverse drug reactions are strongly linked with HLA-B*13: 01 allele in the Thai population

OBJECTIVES

A previous publication in Chinese leprosy patients showed that the HLA-B*13:01 allele is a strong genetic marker for dapsone-induced drug hypersensitivity reactions, however there are no data describing whether HLA-B*13:01 is a valid marker for prediction of dapsone-induced drug hypersensitivity reactions in other ethnicities or nonleprosy patients. The aim of this study is to investigate whether there is an association between HLA genotypes and dapsone-induced severe cutaneous adverse reactions (SCARs) in Thai nonleprosy patients.

PATIENTS AND METHODS

HLA-B genotypes of 15 patients with dapsone-induced SCARs (11 drug reaction with eosinophilia and systemic symptoms, 4 Stevens-Johnson syndrome/toxic epidermal necrolysis), 29 control patients, and 986 subjects from the general Thai population were determined by the reverse PCR sequence-specific oligonucleotides probe.

RESULTS

The HLA-B*13:01 allele was significantly associated with dapsone-induced SCARs compared with dapsone-tolerant controls (odds ratio: 54.00, 95% confidence interval: 7.96-366.16, P=0.0001) and the general population (odds ratio: 26.11, 95% confidence interval: 7.27-93.75, P=0.0001). In addition, HLA-B*13:01 associated with dapsone-induced SJS-TEN (OR: 40.50, 95% confidence interval: 2.78-591.01, P=0.0070) and DRESS (OR: 60.75, 95% confidence interval: 7.44-496.18, P=0.0001).

CONCLUSION

This study demonstrated an association between HLA-B*13:01 and dapsone-induced SCARs including Stevens-Johnson syndrome/toxic epidermal necrolysis and drug reaction with eosinophilia and systemic symptoms in nonleprosy patients. Moreover, these results suggest that the HLA-B*13:01 allele may be a useful genetic marker for prediction of dapsone-induced SCARs in Thai and Han-Chinese populations.

Evaluation of immunomodulatory effects of lamotrigine in BALB/c mice

Modulation of the immune system has recently been shown to be involved in the pharmacological effects of old antiepileptic drugs and in the pathogenesis of epilepsy. Therefore, the most recent guidelines for immunotoxicological evaluation of drugs were consulted to investigate the immunomodulatory effects of lamotrigine, a newer antiepileptic drug, in BALB/c mice. These included the in vivo effects of lamotrigine on delayed-type hypersensitivity (DTH) response to sheep red blood cell (SRBC) antigens, hemagglutination titer assays and hematological changes. In vitro effects of lamotrigine on ConA-induced splenocyte proliferation and cytokine secretion were assessed. The results showed that lamotrigine treatment significantly increased the DTH response to SRBC in the mouse model of this study. This was accompanied by a significant increase in relative monocyte and neutrophil counts and in spleen cellularity. Lamotrigine significantly inhibited ConA-induced splenocyte proliferation in vitro and it significantly inhibited IL-2 and TNF-α secretion in ConA-stimulated splenocytes. In conclusion, the results demonstrated significant immunomodulatory effects of lamotrigine in BALB/c mice. These data could expand the understanding of lamotrigine-induced adverse reactions and its role in modulating the immune system in epilepsy.

Cutaneous Manifestation of Drug Allergy and Hypersensitivity

Drug hypersensitivity reactions may manifest with either organ-specific or systemic symptoms, but cutaneous eruptions are the most common manifestations. Different medications may cause identical skin symptoms, whereas hypersensitivity to a single drug may manifest with various patterns of symptoms depending on the pathomechanism of hypersensitivity. Drug reactions should be also taken into account in the differential diagnosis of numerous skin rashes. Analysis of morphology of drug-induced lesions, about potential immunologic or nonimmunological mechanisms, is important for the final diagnosis. Thus, here the authors present a morphologic approach to the diagnosis of cutaneous drug-induced eruptions.

New Insights into Drug Reaction with Eosinophilia and Systemic Symptoms Pathophysiology

Drug reaction with eosinophilia and systemic symptoms (DRESS), also known as drug-induced hypersensitivity syndrome, is a severe type of cutaneous drug-induced eruption. DRESS may be a difficult disease to diagnose since the symptoms mimic those of cutaneous and systemic infectious pathologies and can appear up to 3 months after the initial culprit drug exposure. The symptoms of DRESS syndrome include rash development after a minimum of 3 weeks after the onset of a new medication, associated with facial edema, lymphadenopathy, and fever. Biological findings include liver abnormalities, leukocytosis, eosinophilia, atypical lymphocytosis, and reactivation of certain human herpes viruses. In DRESS, liver, kidneys, and lungs are frequently involved in disease evolution. Patients with serious systemic involvement are treated with oral corticosteroids, and full recovery is achieved in the majority of cases. DRESS is a rare disease, and little is known about factors that predict its occurrence. The key features of this reaction are eosinophil involvement, the role of the culprit drug, and virus reactivation that trigger an inappropriate systemic immune response in DRESS patients. Interestingly, it was evidenced that at-risk individuals within a genetically restricted population shared a particular HLA loci. In this respect, a limited number of well-known drugs were able to induce DRESS. This review describes the up-to-date advances in our understanding of the pathogenesis of DRESS.

Recent advances in the understanding of severe cutaneous adverse reactions

Severe cutaneous adverse reactions (SCARs) encompass a heterogeneous group of delayed hypersensitivity reactions, which are most frequently caused by drugs. Our understanding of several aspects of SCAR syndromes has evolved considerably over the last decade. This review explores evolving knowledge of the immunopathogenic mechanisms, pharmacogenomic associations, in vivo and ex vivo diagnostics for causality assessment, and medication cross-reactivity data related to SCAR syndromes. Given the rarity and severity of these diseases, multidisciplinary collaboration through large international, national and/or multicentre networks to collect prospective data on patients with SCAR syndromes should be prioritized. This will further enhance a systematized framework for translating epidemiological, clinical and immunopathogenetic advances into preventive efforts and improved outcomes for patients.

Rivaroxaban-Induced Hypersensitivity Syndrome

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Non-immediate Cutaneous Reactions to Beta-Lactams: Approach to Diagnosis

Non-immediate cutaneous reactions (i.e., occurring at least 1 h after the initial drug administration), particularly maculopapular exanthemas and urticarial eruptions, are common during beta-lactam treatments. A T cell-mediated pathogenic mechanism has been demonstrated in some cutaneous reactions, such as maculopapular exanthema, fixed drug eruption, acute generalized exanthematous pustulosis, and drug-induced hypersensitivity syndrome. In the diagnostic work-up, patch testing is useful, together with delayed-reading intradermal testing. Patch tests are a simple and safe diagnostic tool, which in the case of severe reactions should be used as the first line of investigation. However, patch tests are less sensitive than intradermal tests, which are preferable in subjects with mild reactions. Lymphocyte transformation or activation tests and enzyme-linked immunosorbent spot assays can be used as complementary tests. In selected cases of mild or moderate reactions, displaying negative results in the aforesaid allergy tests, a graded challenge with the implicated beta-lactam can be performed.

Multiple cavities with halo sign in a case of invasive pulmonary aspergillosis during therapy for drug-induced hypersensitivity syndrome

A 67-year-old female with rheumatoid arthritis and asthma-chronic obstructive pulmonary disease overlap syndrome was admitted for drug-induced hypersensitivity syndrome (DIHS) caused by salazosulfapyridine. Human herpes virus 6 (HHV-6) variant B was strongly positive on peripheral blood. Multiple cavities with ground grass opacities rapidly emerged predominantly in the upper and middle lobes. She was diagnosed with invasive pulmonary aspergillosis (IPA), and was treated successfully with antifungal agents. Therapeutic systemic corticosteroids, emphysematous change in the lungs, and the worsening of the patient's general condition due to DIHS were considered major contributing factor leading to IPA. HHV-6 reactivation could have an effect on clinical course of IPA. Cavities with halo sign would provide an early clue to IPA in non-neutropenic and immunosuppressive patients.

Outpatient desensitization in selected patients with platinum hypersensitivity reactions

Platinum-based chemotherapies are a standard treatment for both initial and recurrent gynecologic cancers. Given this widespread use, it is important to be aware of the features of platinum hypersensitivity reactions and the subsequent treatment of these reactions. There is also increasing interest in the development of desensitization protocols to allow patients with a history of platinum hypersensitivity to receive further platinum based therapy. In this review, we describe the management of platinum hypersensitivity reactions and the desensitization protocols utilized at our institution. We also describe the clinical categorizations utilized to triage patients to appropriate desensitization protocols.

The HLA-A*31:01 allele: influence on carbamazepine treatment

Carbamazepine (CBZ) is an effective anticonvulsant that can sometimes cause hypersensitivity reactions that vary in frequency and severity. Strong associations have been reported between specific human leukocyte antigen (HLA) alleles and susceptibility to CBZ hypersensitivity reactions. Screening for HLA-B*15:02 is mandated in patients from South East Asia because of a strong association with Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). HLA-A*31:01 predisposes to multiple phenotypes of CBZ hypersensitivity including maculopapular exanthema, hypersensitivity syndrome, and SJS/TEN in a range of populations including Europeans, Japanese, South Koreans and Han Chinese, although the effect size varies between the different phenotypes and populations. Between 47 Caucasians and 67 Japanese patients would need to be tested for HLA-A*31:01 in order to avoid a single case of CBZ hypersensitivity. A cost-effectiveness study has demonstrated that HLA-A*31:01 screening would be cost-effective. Patient preference assessment has also revealed that patients prefer pharmacogenetic screening and prescription of alternative anticonvulsants compared to current standard of practice without pharmacogenetic testing. For patients who test positive for HLA-A*31:01, alternative treatments are available. When alternatives have failed or are unavailable, HLA-A*31:01 testing can alert clinicians to 1) patients who are at increased risk of CBZ hypersensitivity who can then be targeted for more intensive monitoring and 2) increase diagnostic certainty in cases where hypersensitivity has already occurred, so patients can be advised to avoid structurally related drugs in the future. On the basis of the current evidence, we would favor screening all patients for HLA-A*31:01 and HLA-B*15:02 prior to starting CBZ therapy.

Potent NLRP3 Inflammasome Activation by the HIV Reverse Transcriptase Inhibitor Abacavir

There is experimental and clinical evidence that some exanthematous allergic drug hypersensitivity reactions are mediated by drug-specific T cells. We hypothesized that the capacity of certain drugs to directly stimulate the innate immune system may contribute to generate drug-specific T cells. Here we analyzed whether abacavir, an HIV-1 reverse transcriptase inhibitor often inducing severe delayed-type drug hypersensitivity, can trigger innate immune activation that may contribute to its allergic potential. We show that abacavir fails to generate direct innate immune activation in human monocytes but potently triggers IL-1β release upon pro-inflammatory priming with phorbol ester or Toll-like receptor stimulation. IL-1β processing and secretion were sensitive to Caspase-1 inhibition, NLRP3 knockdown, and K⁺ efflux inhibition and were not observed with other non-allergenic nucleoside reverse transcriptase inhibitors, identifying abacavir as a specific inflammasome activator. It further correlated with dose-dependent mitochondrial reactive oxygen species production and cytotoxicity, indicating that inflammasome activation resulted from mitochondrial damage. However, both NLRP3 depletion and inhibition of K⁺ efflux mitigated abacavir-induced mitochondrial reactive oxygen species production and cytotoxicity, suggesting that these processes were secondary to NLRP3 activation. Instead, depletion of cardiolipin synthase 1 abolished abacavir-induced IL-1β secretion, suggesting that mitochondrial cardiolipin release may trigger abacavir-induced inflammasome activation. Our data identify abacavir as a novel inflammasome-stimulating drug allergen. They implicate a potential contribution of innate immune activation to medication-induced delayed-type hypersensitivity, which may stimulate new concepts for treatment and prevention of drug allergies.

A mutually beneficial collaboration between the European Academy of Allergy and Clinical Immunology Junior Members and Clinical and Translational Allergy

The European Academy of Allergy and Clinical Immunology (EAACI) Junior Members (JM) comprise the largest EAACI section with around 4000 clinicians and scientists under 35 years of age working in the field of allergy and clinical immunology. The Junior Member collaboration with Clinical and Translational Allergy Journal is a mutually beneficial relationship providing Junior Members of EAACI with excellent opportunities to publish their work in the Journal, enhance their visibility in their respective field, and get involved with Journal-related activities and processes. In the future, this collaboration will grow, not only by the consolidation of these activities, but also by the implementation of new initiatives, such as a platform for discussing and/or publishing Junior Members’ dissertations in the Journal. From the CTA perspective, the collaboration presents an opportunity to promote a new generation of allergists with experience of conducting and presenting research, with improved skills in critical review.

Enigma: infection or allergy? Vancomycin-induced DRESS syndrome with dialysis-dependent renal failure and cardiac arrest

A man aged 73 years with infective endocarditis presented with septic shock and was started on immediate antimicrobial therapy. His blood culture yielded no organism. Subsequently, he developed a severe allergic reaction to prolonged empirical vancomycin therapy. This manifested as fever, widespread maculopapular rash and severe progressive acute kidney injury ultimately requiring dialysis. In the context of eosinophilia, this was determined to be drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome. Deciphering this complication as allergy in the context of severe infection required extreme caution due to the polarity of treatment with immunosuppression. Ultimately, this was used, with improvement of renal function, resolution of symptoms and absence of recurrence of infection. In summary, we present a case of vancomycin-related DRESS syndrome leading to dialysis-which is unique in the literature-complicating the treatment of culture-negative infective endocarditis.

A fatal case of DRESS induced by strontium ranelate associated with HHV-7 reactivation

We report the first case of drug rash with eosinophilia and systemic symptoms (DRESS) following strontium ranelate (SR) treatment associated with systemic human HHV-7 reactivation. DRESS syndrome is a severe adverse drug-induced reaction presenting as a diffuse maculopapular skin rash with fever, hematological abnormalities (leukocytosis, eosinophilia, and/or atypical lymphocytosis), and multiorgan involvement. In our patient, diagnosis of DRESS was confirmed by the presence of six of the seven diagnostic criteria established in 2006 by the Japanese Research Committee on Severe Cutaneous Adverse Drug Reaction: maculopapular skin rash developing at least 3 weeks after starting therapy with a limited number of drugs, prolonged clinical symptoms after discontinuation of the causative drug, lymphadenopathy, fever, leukocyte abnormalities, and liver abnormalities. The diagnostic criteria of human herpesvirus (HHV)-6 reactivation have not been fulfilled in our patient, but a HHV-7 active infection was demonstrated by the presence of HHV-7 DNA and IgM in the patient's serum. In fact, in some DRESS instances, reactivation of HHVs other than HHV-6 may be detected, including HHV-7, Epstein-Barr virus (EBV), and cytomegalovirus (CMV). Our case underlines that not only HHV-6 but also HHV-7 systemic reactivation may be associated with a more severe and even fatal course of this syndrome.