Drug patch testing in systemic cutaneous drug allergy

Fixed drug eruption-induced balanoposthitis: a case report

Fixed Drug Eruptions (FDE) represent a distinctive type of adverse drug reaction, typically characterized by recurring, sharply demarcated skin lesions occurring at identical sites with each administration of the causative drug. A less frequent, albeit significant manifestation of FDE, is balanoposthitis, an inflammatory condition affecting the glans penis and prepuce. This rare case report explores the clinical presentation, diagnosis, and therapeutic management of FDE-induced balanoposthitis in a 34-year-old male patient who developed this condition following azithromycin administration to treat a pulmonary infection. The patient's distinctive symptoms, coupled with a medical history of similar antibiotic-induced reactions, pointed strongly towards an FDE diagnosis. Management entailed immediate discontinuation of the offending drug and initiation of symptomatic treatment, culminating in a positive therapeutic outcome. This case illuminates the potential of commonly prescribed medications, such as antibiotics, to incite balanoposthitis via FDE. It underscores the critical need for healthcare professionals to include FDE in their differential diagnosis for balanoposthitis, especially when patient exposure to high-risk medications is evident. Furthermore, the report emphasizes the pressing requirement for additional research to elucidate the pathogenesis of FDE-induced balanoposthitis and to devise effective therapeutic and preventive measures.

Patch testing in Drug reaction with eosinophilia and systemic symptoms (DRESS): a literature review

The literature on positive patch test results in drug reaction with eosinophilia and systemic symptoms (DRESS) is reviewed. 105 drugs were identified that have together caused 536 positive patch tests in 437 patients suffering from DRESS. By far most reactions (n=145) were caused by carbamazepine, followed by amoxicillin, isoniazid, phenytoin, ethambutol, fluindione, phenobarbital, rifampicin, and ceftriaxone; 43 drugs each caused a single case only. The drug classes causing the highest number of reactions are anticonvulsants (39%), beta-lactam antibiotics (20%), antituberculosis agents (11%), non-beta-lactam antibiotics (6%) and iodinated contrast media (5%). The sensitivity of patch testing (percentage of positive reactions) is high for anticonvulsants (notably carbamazepine), beta-lactam antibiotics (notably amoxicillin) and possibly iodinated contrast media. Allopurinol and sulfasalazine frequently cause DRESS, but never give positive patch tests. Patch testing in DRESS appears to be safe, although mild recurrence of DRESS symptoms, mostly skin reactions, may not be rare. Multiple drug hypersensitivity was found to occur in 16% of all patients, but it is argued that the true frequency is (far) higher. Clinical aspects of DRESS, including diagnosing the disease and identifying culprit drugs (patch tests, intradermal tests, in vitro tests, challenge tests) are also provided, emphasizing the role of patch testing. This article is protected by copyright. All rights reserved.

Patch Testing in Drug Eruptions: Practical Aspects and Literature Review of Eruptions and Culprit Drugs

ABSTRACT

There is overwhelming evidence that many delayed cutaneous adverse drug reactions (beginning >6 hours after drug intake) are mediated by delayed-type (type IV) hypersensitivity, including maculopapular eruptions, erythroderma, symmetrical drug-related intertriginous and flexural exanthema/baboon syndrome, eczematous eruptions, fixed drug eruptions, acute generalized exanthematous pustulosis, and drug reaction with eosinophilia and systemic symptoms/drug-induced hypersensitivity syndrome. Therefore, after resolution of the reaction, patch tests should be performed as first diagnostic method to identify the culprit drug(s). This article provides tools to perform drug patch tests properly and safely, discussing clinical history, indications, procedure, drug patch test materials, sensitivity, the meaning of negative patch tests, and safety of the procedure. In addition, a literature review of eruptions and culprit drugs is provided in tabular format.

Case Report: DRESS Syndrome Induced by Two Antituberculosis Drugs in an 8-Year-Old Girl

DRESS syndrome is defined as drug-induced hypersensitivity syndrome with rash, eosinophilia, and systemic symptoms. This syndrome is mostly associated with anticonvulsants, antibacterial and anti-inflammatory drugs. DRESS syndrome is a rare disease and is more frequently seen in adults. We present the first case report of DRESS syndrome in an 8-year-old girl, after 3 months of treatment with isoniazid and rifampicin. After discontinuation of drugs and a short course of prednisolone the girl recovered. After 5 years of follow-up, she is healthy and has no complaints but patch tests with isoniazid and rifampicin remain positive. The reported case emphasizes the importance of thorough medical history and including drug reactions in differential diagnosis.

Delabeling Delayed Drug Hypersensitivity: How Far Can You Safely Go?

Delayed immune-mediated adverse drug reactions (IM-ADRs) are defined as reactions occurring more than 6 hours after dosing. They include heterogeneous clinical phenotypes that are typically T-cell-mediated reactions with distinct mechanisms across a wide spectrum of severity from benign exanthems through to life-threatening cutaneous or organ-specific diseases. For mild reactions such as benign exanthem, considerations for delabeling are similar to immediate reactions and may include a graded or single-dose drug challenge with or without preceding skin or patch testing. Evaluation of challenging cases such as the patient who is on multiple drugs at the time a severe delayed IM-ADR occurs should prioritize clinical ascertainment of the most likely phenotype and implicated drug(s). Although not widely available and validated, procedures such as patch testing, delayed intradermal skin testing, and laboratory-based functional drug assays or genetic (human leukocyte antigen) testing may provide valuable information to further help risk stratify patients and identify the likely implicated and/or cross-reactive drug(s). The decision to use a drug challenge as a diagnostic or delabeling tool in a patient with a severe delayed IM-ADR should weigh the risk-benefit ratio, balancing the severity and priority for the treatment of the underlying, and the availability of alternative efficacious and safe treatments.

Eczematous Drug Eruptions

Eczematous drug eruptions are a heterogenous group of skin reactions that resemble eczema both clinically and histologically. We reviewed the literature and cataloged the systemically administered medications that cause these eruptions, along with their characteristic clinical presentations. We identified three primary pathophysiologic etiologies: (1) cutaneous immunomodulation, (2) skin dehydration, and (3) delayed hypersensitivity. Notably, eczematous eruptions caused by altered immunity in the skin may be increasing in incidence as some responsible drugs, in particular biologic therapies (such as tumor necrosis factor-α and interleukin-17 inhibitors) and targeted cancer treatments (including immune checkpoint inhibitors and epidermal growth factor receptor inhibitors), become more commonly employed in clinical practice. Other notable causes of eczematous eruptions include antiviral agents for hepatitis C virus and cardiovascular medications in elderly individuals, and notable subtypes of eczematous reactions include systemic contact dermatitis and photoallergic reactions, which are also discussed. The diagnostic gold standard is drug rechallenge and most reactions may be treated effectively with emollients, topical corticosteroids, and oral antihistamines.

Delayed hypersensitivity to antiepileptic drugs in children

BACKGROUND

Antiepileptic drugs (AEDs) are widely used for the treatment of epilepsy, but they can be associated with the development of mainly delayed/non-immediate hypersensitivity reactions (HRs). Although these reactions are usually cutaneous, self-limited, and spontaneously resolve within days after drug discontinuation, sometime HR reactions to AEDs can be severe and life-threatening.

AIM

This paper seeks to show examples on practical management of AED HRs in children starting from a review of what it is already known in literature.

RESULTS

Risk factors include age, history of previous AEDs reactions, viral infections, concomitant medications, and genetic factors. The diagnostic workup consists of in vivo (intradermal testing and patch testing) and in vitro tests [serological investigation to exclude the role of viral infection, lymphocyte transformation test (LTT), cytokine detection in ELISpot assays, and granulysin (Grl) in flow cytometry. Treatment is based on a prompt drug discontinuation and mainly on the use of glucocorticoids.

CONCLUSION

Dealing with AED HRs is challenging. The primary goal in the diagnosis and management of HRs to AEDs should be trying to accurately identify the causal trigger and simultaneously identify a safe and effective alternative anticonvulsant. There is therefore an ongoing need to improve our knowledge of HS reactions due to AED medications and in particular to improve our diagnostic capabilities.

Evaluation of drug patch tests in children

Background: Patch tests are used to diagnose nonimmediate T-cell-mediated drug hypersensitivity reactions. The aim of this study was to evaluate the results of patch tests performed with suspect drugs in children. Methods: Patients < 18 years of age who had a drug patch test at the pediatric allergy outpatient clinic of our hospital between January 2014 and January 2020 were included in the study. Age, sex, culprit drug(s), reaction characteristics, and patch test results were recorded from the patients' files. Results: A total of 105 drug patch tests were performed on 71 patients during the study period. The patients' median age was 7 years (interquartile range, 4-11 years), and 57.7% (n = 41) were boys. Twenty-three patients (32.3%) had severe cutaneous adverse reaction (Stevens-Johnson syndrome in 11, drug reaction with eosinophilia and systemic symptoms in 9, and acute generalized exanthematous pustulosis in 3 patients), 45 (63.3%) had maculopapular rashes, and 3 (4.2%) had fixed drug eruption. A total of 20 patch test results (28%) were positive: 18 of 44 patch tests (40.9%) with antiepileptic drugs and 2 of 48 patch tests (4.1%) with antibiotics. Positive results were obtained in 23% of the patch tests (6/26) in 20 patients with severe cutaneous adverse reactions and in 17.7% of the patch tests (14/79) in 51 patients with mild cutaneous reactions. No adverse reactions occurred during or after the patch tests. Conclusion: In our study, patch test positivity was more common with antiepileptic drugs and in patients with severe cutaneous drug reaction.

S3 guidelines: Epicutaneous patch testing with contact allergens and drugs - Short version, Part 1

Epicutaneous patch testing is the diagnostic standard for the detection of allergic contact dermatitis. The present guidelines are aimed at residents and board-certified physicians in the fields of dermatology and allergology as well as other medical specialties involved in establishing the indication for patch testing and its execution in patients with contact dermatitis and other forms of delayed-type hypersensitivity. The target audience also includes other health care providers and insurance funds. Based on a systematic literature search and a formal consensus process (S3), the guidelines were developed by dermatologists in collaboration with pediatricians, occupational medicine physicians, nursing staff as well as patient representatives. The systematic methodological approach and appraisal of evidence upon which the recommendations are based are outlined in a separate method report that also contains evidence tables. The guidelines address general aspects of patch testing as well as medicolegal issues. The recommendations given relate to topics such as the indication for patch testing, informed patient consent, as well as the choice of test substances, test chambers and test site, duration of exposure, reading times and interpretation of test reactions. Furthermore, recommendations are provided with respect to endogenous and exogenous factors, specific patient groups (children, pregnant women, immunosuppressed individuals) as well as possible risks and adverse events associated with patch testing using contact allergens. Note: This publication is part 1 of the short version of the S3 guidelines for "Epicutaneous patch testing using contact allergens and drugs" (registry no. 013 - 018; date: March 20, 2019; valid until December 31, 2021). Part 2 of the short version will be published in the next issue. The long version of these guidelines can be accessed at www.awmf.org. The method report is available as online publication (https://www.awmf.org/leitlinien/detail/ll/013-018.html) and contains the evidence tables in its appendix.

A rare case report of apixaban-induced lichenoid eruption

With recent increase in the use of direct oral anticoagulants (DOACs), several new cases of adverse drug reactions (ADRs) have been identified in pharmacovigilance surveys. These ADRs can result in significant mortality and morbidity if not identified and treated promptly. It is important for physicians to recognize that immunologically mediated delayed hypersensitivity reactions, although rare in occurrence, can have significant impact on patient's quality of life. To the best of our knowledge, we report the first case of lichenoid eruption associated with apixaban. We further provide evidence of tolerance to rivaroxaban in the same patient.

PLAIN LANGUAGE SUMMARY

Apixaban-induced lichenoid eruption Well documented case reports, although providing evidence of probable causal relationship between a drug and specific adverse drug reactions (ADRs), can increase awareness amongst clinicians treating patients with direct oral anticoagulants (DOACs), especially with its rapid utilization. Rare ADRs are difficult to detect as clinical trials of DOACs lacked enough patient sample, making post-marketing reporting of such events important so both patients and clinicians can be vigilant to help with prompt recognition of such symptoms. We report the first case of lichenoid eruption hypersensitivity reaction associated with apixaban in patient with tolerance to rivaroxaban.

Hypersensitivity reactions to antiepileptic drugs in children

BACKGROUND

Antiepileptic drugs (AEDs) can cause hypersensitivity reactions in children. These reactions are mainly cutaneous, self-limiting, and benign, but life-threatening severe cutaneous adverse reactions can occur. Infections can lead to skin eruptions and mimic drug hypersensitivity reactions, if a drug is taken at the same time. The aims of our study were to confirm or rule out the diagnosis of hypersensitivity reactions to AEDs in children and to detect an infection which mimics these reactions.

METHODS

A prospective survey was conducted in a group of 100 children with histories of hypersensitivity reactions to AEDs by performing patch tests, delayed-reading intradermal test, and, in case of negative results, challenge test. In all children, a study was performed to detect infections by viruses or Mycoplasma pneumoniae.

RESULTS

Maculopapular exanthema and delayed-appearing urticaria were the most reported hypersensitivity reactions to AEDs. Sixty-six (66%) of 100 children had confirmed hypersensitivity reactions to AEDs. Fifty-nine children had positive patch test. No children had positive challenge tests. The most common AEDs causing hypersensitivity reactions were carbamazepine (45.4%) and lamotrigine (43.6%). Thirty-two children had positive tests for viruses or M pneumoniae, and nine of them had also a positive allergy work-up.

CONCLUSION

Considering that there are no specific tests to distinguish between a viral infection and hypersensitivity reactions to AEDs in the acute phase, a diagnostic work-up should be performed in all children with suspected hypersensitivity reactions to AEDs, as well as infectious agent study, to remove a false label of hypersensitivity.

Recent developments in drug hypersensitivity in children

Introduction: Drug allergy is an important public health problem that causes 0.4-10.3% of hospital admissions in children. The epidemiology, clinical spectrum, diagnosis, and management of drug hypersensitivity reactions (DHRs) differ in pediatric and adult patients. However, the same algorithms used in adults have often been applied in the pediatric population due to a lack of evidence in the literature. Areas covered: In this review, we aimed to discuss recent developments in the area of pediatric DHRs based on the growing body of literature advancing our understanding of the epidemiology, clinical aspects, and diagnostic approaches to DHRs in children. Expert opinion: Misdiagnosis, under-diagnosis, and self-diagnosis are common problems related to drug allergies in children. Viral infections are particularly frequent in children and make diagnosis difficult. Identifying true DHR is a key step in the management of drug allergy in children. Therefore, a complete allergy work-up with standardized drug allergy tests is necessary. In order to eliminate non-standardized tests, future studies including larger numbers of children should be conducted to determine more accurate standardized tests for diagnosing DHRs in the pediatric population.

Lichen planus and lichenoid dermatoses: Clinical overview and molecular basis

Deriving from the Greek word λειχήν for "tree moss" and the Latin word planus for "planar," lichen planus is a relatively uncommon and heterogeneous cutaneous disorder that typically develops in middle-aged adults. Despite the significant clinical burden associated with the disorder, little well-conducted molecular research has been undertaken, possibly because of heterogeneity impeding consistent and confident phenotyping. The multiple variants of lichenoid disease bear overlapping clinical and pathologic features despite manifesting as distinct clinical disorders. The first article in this 2-part continuing medical education series provides a comprehensive overview of the clinical and pathologic characteristics of cutaneous lichenoid dermatoses and links these manifestations to recent advances in our understanding of the underlying pathobiology of such diseases.

Antibiotic allergy

Antibiotics are the commonest cause of life-threatening immune-mediated drug reactions that are considered off-target, including anaphylaxis, and organ-specific and severe cutaneous adverse reactions. However, many antibiotic reactions documented as allergies were unknown or not remembered by the patient, cutaneous reactions unrelated to drug hypersensitivity, drug-infection interactions, or drug intolerances. Although such reactions pose negligible risk to patients, they currently represent a global threat to public health. Antibiotic allergy labels result in displacement of first-line therapies for antibiotic prophylaxis and treatment. A penicillin allergy label, in particular, is associated with increased use of broad-spectrum and non-β-lactam antibiotics, which results in increased adverse events and antibiotic resistance. Most patients labelled as allergic to penicillins are not allergic when appropriately stratified for risk, tested, and re-challenged. Given the public health importance of penicillin allergy, this Review provides a global update on antibiotic allergy epidemiology, classification, mechanisms, and management.

Drug Allergy

Drug allergy is commonly encountered in clinical practice. It is an immunological response to a pharmaceutical agent. The clinical presentation can vary from mild cutaneous reactions to life-threatening conditions such as Stevens-Johnson syndrome and toxic epidermal necrolysis. Diagnosis is most often clinical, but investigations such as measurement of immunoglobulin E, patch testing, and skin biopsy may be required. In patients with a known drug allergy, the offending drug should be avoided. [Pediatr Ann. 2018;47(10):e419-e425.].

Drug allergy

Drug allergy encompasses a spectrum of immunologically-mediated hypersensitivity reactions with varying mechanisms and clinical presentations. This type of adverse drug reaction not only affects patient quality of life, but may also lead to delayed treatment, unnecessary investigations, and even mortality. Given the myriad of symptoms associated with the condition, diagnosis is often challenging. Therefore, referral to an allergist experienced in the identification, diagnosis and management of drug allergy is recommended if a drug-induced allergic reaction is suspected. Diagnosis relies on a careful history and physical examination and, in some instances, skin testing and graded challenges. Induction of drug tolerance procedures may also be required. The most effective strategy for the management of drug allergy is avoidance or discontinuation of the offending drug. When available, alternative medications with unrelated chemical structures should be substituted. Cross-reactivity among drugs should be taken into consideration when choosing alternative agents. Additional therapy for drug hypersensitivity reactions is largely supportive and may include topical corticosteroids, oral antihistamines and, in severe cases, systemic corticosteroids. In the event of anaphylaxis, the treatment of choice is injectable epinephrine. If a particular drug to which the patient is allergic is indicated and there is no suitable alternative, induction of drug tolerance procedures may be considered to induce temporary tolerance to the drug. This article provides a background on drug allergy and strategies for the diagnosis and management of some of the most common drug-induced allergic reactions, such as penicillin, sulfonamides, cephalosporins, radiocontrast media, local anesthetics, general anesthetics, acetylsalicylic acid and non-steroidal anti-inflammatory drugs, and therapeutic monoclonal antibodies.

Patch testing and cross sensitivity study of adverse cutaneous drug reactions due to anticonvulsants: A preliminary report

AIM

To evaluate the utility of patch test and cross-sensitivity patterns in patients with adverse cutaneous drug reactions (ACDR) from common anticonvulsants.

METHODS

Twenty-four (M:F = 13:11) patients aged 18-75 years with ACDR from anticonvulsants were patch tested 3-27 mo after complete recovery using carbamazepine, phenytoin, phenobarbitone, lamotrigine, and sodium valproate in 10%, 20% and 30% conc. in pet. after informed consent. Positive reactions persisting on D3 and D4 were considered significant.

RESULTS

Clinical patterns were exanthematous drug rash with or without systemic involvement (DRESS) in 18 (75%), Stevens-Johnsons syndrome/toxic epidermal necrolysis (SJS/TEN) overlap and TEN in 2 (8.3%) patients each, SJS and lichenoid drug eruption in 1 (4.2%) patient each, respectively. The implicated drugs were phenytoin in 14 (58.3%), carbamazepine in 9 (37.5%), phenobarbitone in 2 (8.3%), and lamotrigine in 1 (4.7%) patients, respectively. Twelve (50%) patients elicited positive reactions to implicated drugs; carbamazepine in 6 (50%), phenytoin alone in 4 (33.3%), phenobarbitone alone in 1 (8.3%), and both phenytoin and phenobarbitone in 1 (8.33%) patients, respectively. Cross-reactions occurred in 11 (92%) patients. Six patients with carbamazepine positive patch test reaction showed cross sensitivity with phenobarbitone, sodium valproate and/or lamotrigine. Three (75%) patients among positive phenytoin patch test reactions had cross reactions with phenobarbitone, lamotrigine, and/or valproate.

CONCLUSION

Carbamazepine remains the commonest anticonvulsant causing ACDRs and cross-reactions with other anticonvulsants are possible. Drug patch testing appears useful in DRESS for drug imputability and cross-reactions established clinically.

Eosinophilic Drug Allergy

While peripheral or tissue eosinophilia may certainly characterize drug eruptions, this feature is hardly pathognomonic for a medication-induced etiology. While delayed drug hypersensitivity reactions with prominent eosinophilic recruitment have been typically classified as type IVb reactions, their pathophysiology is now known to be more complex. Eosinophilic drug reactions have a diversity of presentations and may be benign and self-limited to severe and life-threatening. The extent of clinical involvement is also heterogeneous, ranging from isolated peripheral eosinophilia or single organ involvement (most often the skin and lung) to systemic disease affecting multiple organs, classically exemplified by drug-reaction with eosinophilia and systemic symptoms (DRESS). The spectrum of implicated medications in the causation of DRESS is ever expanding, and multiple factors including drug metabolites, specific HLA alleles, herpes viruses, and immune system activation have been implicated in pathogenesis. Due to this complex interplay of various factors, diagnostic workup in terms of skin and laboratory testing has not been validated. Similarly, the lack of controlled trials limits treatment options. This review also describes other localized as well as systemic manifestations of eosinophilic disease induced by various medication classes, including their individual pathophysiology, diagnosis, and management. Given the multitude of clinical patterns associated with eosinophilic drug allergy, the diagnosis can be challenging. Considerable deficits in our knowledge of these presentations remain, but the potential for severe reactions should be borne in mind in order to facilitate diagnosis and institute appropriate management.

Acute Generalized Exanthematous Pustulosis: Pathogenesis, Genetic Background, Clinical Variants and Therapy

Acute generalized exanthematous pustulosis (AGEP) is a severe, usually drug-related reaction, characterized by an acute onset of mainly small non-follicular pustules on an erythematous base and spontaneous resolution usually within two weeks. Systemic involvement occurs in about 20% of cases. The course is mostly benign, and only in rare cases complications lead to life-threatening situations. Recent studies highlight the importance of genetic variations in interleukin-36 receptor antagonist gene (IL-36RN) in the pathogenesis of this disease. The physiopathology of AGEP remains unclear, but an involvement of innate and acquired immune cells together with resident cells (keratinocytes), which recruit and activate neutrophils via production of cytokines/chemokines such as IL-17, IL-36, granulocyte-macrophage colony-stimulating factor (GM-CSF), tumor necrosis factor alpha (TNFα) and chemokine (C-X-C motif) ligand 8 (CXCL8)/IL-8, has been postulated. Treatment is based on the removal of the causative drug, supportive care, infection prevention and use of potent topical or systemic steroids.

Contact dermatitis: a practice parameter-update 2015

This parameter was developed by the Joint Task Force on Practice Parameters, which represents the American Academy of Allergy, Asthma & Immunology (AAAAI); the American College of Allergy, Asthma & Immunology (ACAAI); and the Joint Council of Allergy, Asthma & Immunology. The AAAAI and the ACAAI have jointly accepted responsibility for establishing "Contact Dermatitis: A Practice Parameter-Update 2015." This is a complete and comprehensive document at the current time. The medical environment is changing and not all recommendations will be appropriate or applicable to all patients. Because this document incorporated the efforts of many participants, no single individual, including members serving on the Joint Task Force, are authorized to provide an official AAAAI or ACAAI interpretation of these practice parameters. Any request for information or interpretation of this practice parameter by the AAAAI or ACAAI should be directed to the Executive Offices of the AAAAI, the ACAAI, and the Joint Council of Allergy, Asthma & Immunology. These parameters are not designed for use by the pharmaceutical industry in drug development or promotion. Previously published practice parameters of the Joint Task Force on Practice Parameters for Allergy & Immunology are available at http://www.JCAAI.org or http://www.allergyparameters.org.

[Delayed-type cutaneous drug reactions. Pathogenesis, clinical features and histology]

BACKGROUND

Cutaneous reactions to drugs can be subdivided in different ways. In addition to the standard classification according to the etiopathogenesis there are also classifications based predominantly on morphological criteria. The majority of drug-related cutaneous adverse reactions are immunological reactions which are collectively classified under the term hypersensitivity. These reactions are based on drug-specific immunoglobulin E (IgE) or cell-mediated mechanisms, not on the mechanism of action of the drug and are unpredictable. Delayed type reactions to drugs are forms of type IV T-cell mediated hypersensitivity. A prerequisite is a stable association of a pharmaceutical substance with a protein so that hapten-protein conjugates can be produced. The most common clinical symptom is maculopapular (morbilliform) drug-related exanthema. This article also examines lichen planus like drug reaction and drug-induced (hematogenic) allergic contact dermatitis in more detail.

DIAGNOSTICS

The diagnostics are never trivial but also include the differentiation from viral exanthema and initial phases of severe cutaneous adverse reactions, such as toxic epidermal necrolysis. In addition to the morphological classification, the final diagnosis encompasses the interpretation of histopathological alterations in the skin biopsy, analysis of patient medication history, laboratory results and inclusion of data from the literature. Patch tests can also have additional diagnostic benefits. In vitro tests which involve the cellular incubation of the drug responsible should be reserved for specialized laboratories. A prerequisite for successful treatment is immediate termination of the drug responsible.

THERAPY AND PROGNOSIS

Therapy is symptomatic with topical and also short-term systemic steroids and antihistamines. The prognosis is very good.

[Acute generalized exanthematous pustulosis]

CLINICAL FEATURES

Acute generalized exanthematous pustulosis (AGEP) is a reaction pattern mostly caused by drugs. It is characterized by the rapid occurrence of dozens to thousands pinhead-sized, non-follicular, sterile pustules on a slightly edematous erythematous base, commonly with accentuation in the major flexures and usually accompanied by a facial edema, fever and leukocytosis. Histology reveals spongiform subcorneal and/or intraepidermal pustules, an inflammatory infiltrate consisting of neutrophils and often eosinophils and frequently a marked edema of the papillary dermis.

TRIGGERS

Even if in single case reports a large number of drugs has been described as triggers for AGEP, larger studies have revealed a list with an elevated risk to cause the reaction which includes antibacterial agents like ampicillin/amoxicillin, quinolones, pristinamycin, anti-infective sulfonamides, the antimycotic drug terbinafine, (hydroxy)chloroquine, and diltiazem. In some cases infections have been reported as triggers.

CLINICAL COURSE, PROGNOSIS AND TREATMENT

AGEP is an acute and--especially in patients with concomitant diseases--sometimes severe reaction. Withdrawal of the causative agent usually leads to a rapid and complete resolution--even without further specific therapy.

Acute generalized exanthematous pustulosis associated with tigecycline

Acute generalized exanthematous pustulosis (AGEP) is a severe and rare eruption that develops mostly from factors related to drugs. It is characterized by a fever and a pustular eruption on the erythematous skin with an acute onset and without follicular localization. Etiopathogenesis has not yet been fully explained. Although it is similar to pustular psoriasis, its clinical, historical and histopathological characteristics are different. In this article, we present a case of AGEP associated with tigecycline that developed in a patient followed up in the intensive care unit for three months with an intra-abdominal injury after a trauma and Acinetobacter baumannii infection.

Topical promethazine side effects: our experience and review of the literature

Promethazine hydrochloride is a first-generation H1 receptor antagonist, antihistamine, and antiemetic medication that can also have strong sedative effects. The apparent ability of topical H1r/2r antagonists to target epidermal H1/2r was translated into increased efficacy in the treatment of inflammatory dermatoses, likely due to decreased inflammation and enhanced barrier function.

Classification and practical approach to the diagnosis and management of hypersensitivity to nonsteroidal anti-inflammatory drugs

Hypersensitivity reactions to aspirin (acetylsalicylic acid) and other nonsteroidal anti-inflammatory drugs (NSAIDs) constitute only a subset of all adverse reactions to these drugs, but due to their severity pose a significant burden to patients and are a challenge to the allergist. In susceptible individuals, NSAIDs induce a wide spectrum of hypersensitivity reactions with various timing, organ manifestations, and severity, involving either immunological (allergic) or nonimmunological mechanisms. Proper classification of reactions based on clinical manifestations and suspected mechanism is a prerequisite for the implementation of rational diagnostic procedures and adequate patient management. This document, prepared by a panel of experts from the European Academy of Allergy and Clinical Immunology Task Force on NSAIDs Hypersensitivity, aims at reviewing the current knowledge in the field and proposes uniform definitions and clinically useful classification of hypersensitivity reactions to NSAIDs. The document proposes also practical algorithms for the diagnosis of specific types of NSAIDs hypersensitivity (which include drug provocations, skin testing and in vitro testing) and provides, when data are available, evidence-based recommendations for the management of hypersensitive patients, including drug avoidance and drug desensitization.

Photodistributed erythema multiforme

Although the existence of photodistributed erythema multiforme has been recognized for years, few cases have been described to date. It is an uncommon, and probably underdiagnosed, skin disorder that can affect individuals of both sexes and all ages. It has been associated with drugs, reactivation of herpes simplex virus infection, and polymorphous light eruption. A diagnosis is made on the basis of history, physical examination, histology, and phototesting. The condition runs a benign, self-limiting course but patients may experience outbreaks for several years if the causative agent is not eliminated. It is treated symptomatically and patients are advised to avoid triggers and excessive sun exposure.

Management of multiple drug allergies in children

Children with multiple drug allergies are likely to require treatment with one or more of the drugs to which they may have had a reaction, when there is no alternate effective drug available. Detailed review of their history and/or use of appropriate diagnostic studies will help determine the potential safety of readministering the desired drug as well as the method for its readministration, most likely in the form of a drug challenge or desensitization. A practical approach to the diagnosis and treatment of children with multiple drug allergies is described in this review.

Definitions and mechanisms of drug hypersensitivity

Adverse drug reactions are a difficult problem faced by clinicians in everyday practice. The mechanisms of drug hypersensitivity are not well understood. This is reflected by difficulties in their classification, which is mainly based upon the current knowledge of immunologic and nonimmunologic mechanisms, onset of symptoms (immediate or nonimmediate) and morphology. For the individual patient, the correct diagnosis and classification is important because strict avoidance of the offending drug might be of vital importance. Considerable experience is required to guide management, to interpret results of investigations and to undertake drug challenges. This article summarizes the current knowledge regarding definitions and mechanisms. However, the field of drug hypersensitivity is rapidly expanding. Modern drugs such as biological agents bare hypersensitivity risks that are potentially mediated by, so far, unknown mechanisms.

Immunologic evaluation of drug allergy

Hypersensitivity drug reactions (HDR) consist of an individual abnormal response with the involvement of the immunological system. In addition to specific immunological mechanisms where specific antibodies or sensitised T cells participate, release of inflammatory mediators by non-specific immunological recognition may also occur. Within this category are one of the most common groups of drugs, the non-steroidal anti-inflammatory drugs. In addition to chemical drugs new emerging ones with an increasing protagonism are biological agents like humanised antibodies and others. For IgE dependent reactions both in vivo and in vitro tests can be used for the immunological evaluation. Sensitivity of these is not optimal and very often a drug provocation test must be considered for knowing the mechanism involved and/or establishing the diagnosis. For non-immediate reactions also both in vivo and in vitro tests can be used. Sensitivity for in vivo tests is generally low and in vitro tests may be needed for the immunological evaluation. Immunohistochemical studies of the affected tissue enable a more precise classification of non-immediate reactions. The monitorization of the acute response of the reactions has given clues for understanding these reactions and has promising results for the future of the immunological evaluation of HDR.

A patch testing and cross-sensitivity study of carbamazepine-induced severe cutaneous adverse drug reactions

BACKGROUND

The usefulness of the drug patch testing for Stevens-Johnson syndrome and toxic epidermal necrolysis (SJS/TEN) is still controversial. Recent studies have shown that HLA-B*1502 is strongly associated with CBZ-SJS/TEN in Chinese and Southeast Asian populations.

OBJECTIVE

To evaluate the usefulness of patch tests for patients with carbamazepine (CBZ)-induced SJS, TEN and drug reaction with eosinophilia and systemic symptoms (DRESS) and the cross-reactivity in patch tests among the aromatic antiepileptic drugs.

METHODS

We measure the frequency of positive patch test reactions and cross-sensitivity to structure-related aromatic anti-epileptic drugs (AEDs) for patients after SJS/TEN or DRESS episodes caused by CBZ. CBZ and other structure-related AEDs used for patch testing were prepared in 10% and 30% petrolatum. Secondary measures included the association of HLA-B*1502 genotype and frequency of possible side effects from the patch tests.

RESULTS

Positive patch test reactions to 30% CBZ in the CBZ-SJS/TEN were 62.5% (10/16), and 70% (7/10) in the CBZ-DRESS. None of the 10 healthy controls displayed a positive reaction to tested agents. Cross-sensitivity to other aromatic AEDs was observed in both the CBZ-SJS/TEN and the CBZ-DRESS. Only the HLA-B*1502 genotype was present and strongly associated with the CBZ-SJS/TEN, but not with the CBZ-DRESS.

CONCLUSION

Drug patch testing is a safe and useful method for the identification of CBZ as the culprit drug of SJS/TEN as well as DRESS. Testing of chemically or pharmacologically related AEDs may provide information on cross-reactivity for these patients.

A case of celecoxib induced acute generalized exanthematous pustulosis

Acute generalized exanthematous pustulosis (AGEP) is manifested by rapid development of many sterile, nonfollicular pustules on a background of edematous erythema. More than 90 percent of AGEP are induced by medication, mostly antibiotics. Drug patch test can be helpful in the diagnosis of AGEP. This paper reports the first case of celecoxib-induced AGEP confirmed by patch test in Korean literature.

Drug allergy

Drug allergy encompasses a spectrum of immunologically-mediated hypersensitivity reactions with varying mechanisms and clinical presentations. This type of adverse drug reaction (ADR) not only affects patient quality of life, but may also lead to delayed treatment, unnecessary investigations, and even mortality. Given the myriad of symptoms associated with the condition, diagnosis is often challenging. Therefore, referral to an allergist experienced in the identification, diagnosis and management of drug allergy is recommended if a drug-induced allergic reaction is suspected. Diagnosis relies on a careful history and physical examination. In some instances, skin testing, graded challenges and induction of drug tolerance procedures may be required.

The most effective strategy for the management of drug allergy is avoidance or discontinuation of the offending drug. When available, alternative medications with unrelated chemical structures should be substituted. Cross-reactivity among drugs should be taken into consideration when choosing alternative agents. Additional therapy for drug hypersensitivity reactions is largely supportive and may include topical corticosteroids, oral antihistamines and, in severe cases, systemic corticosteroids. In the event of anaphylaxis, the treatment of choice is injectable epinephrine. If a particular drug to which the patient is allergic is indicated and there is no suitable alternative, induction of drug tolerance procedures may be considered to induce temporary tolerance to the drug.

This article provides a backgrounder on drug allergy and strategies for the diagnosis and management of some of the most common drug-induced allergic reactions, such allergies to penicillin, sulfonamides, cephalosporins, radiocontrast media, local anesthetics, general anesthetics, acetylsalicylic acid (ASA) and non-steroidal anti-inflammatory drugs.

Skin manifestations of drug allergy

Cutaneous adverse drug reactions range from mild to severe and from those localized only to skin to those associated with systemic disease. It is important to distinguish features of cutaneous drug reactions which help classify the underlying mechanism and likely prognosis as both of these influence management decisions, some of which necessarily have to be taken rapidly. Severe cutaneous reactions are generally T cell-mediated, yet this immunological process is frequently poorly understood and principles for identification of the culprit drug are different to those of IgE mediated allergic reactions. Furthermore, intervention in severe skin manifestations of drug allergy is frequently necessary. However, a substantial literature reports on success or otherwise of glucocorticoids, cyclophsphamide, ciclosporin, intravenous immunoglobulin and anti-tumour necrosis factor therapy for the treatment of toxic epidermal necrolysis without clear consensus. As well as reviewing the recommended supportive measures and evidence base for interventions, this review aims to provide a mechanistic overview relating to a proposed clinical classification to assist the assessment and management of these complex patients.