EAACI position paper on how to classify cutaneous manifestations of drug hypersensitivity

[Swissallergy]

Abstract Drug hypersensitivity reactions (DHRs) are common, and the skin is by far the most frequently involved organ with a broad spectrum of reaction types. The diagnosis of cutaneous DHRs (CDHR) may be difficult because of multiple differential diagnoses. A correct classification is important for the correct diagnosis and management. With these guidelines, we aim to give precise definitions and provide the background needed for doctors to correctly classify CDHR. 1 | INTRODUCTION Drug hypersensitivity reactions (DHRs) affect more than 7% of the population and are a concern for doctors and patients alike.

1,2 The skin is by far the most frequently involved organ,1,3 with a broad spectrum of reaction types with different morphology, chronology and mecha- nisms.4 Different entities have not only unique clinical features, but also have own implications for causative drugs, diagnostic methods and management. We have described these entities where differences in clinical presentations and prognosis are clear, for example FDE (fixed drug eruption), DRESS (drug reaction with eosinophilia and systemic symptoms), SJS/TEN (Stevens‐Johnson syndrome/toxic epidermal necrolysis) and anaphylaxis.

For benign exanthems, a subclassification has been attempted (eg morbilliform, lichenoid or maculopapular), but these terms are descriptive only because there is no evidence of pathologic or prognostic implications to distinguish the benign phenotypes. Therefore, we have collectively labelled all benign exanthems as maculopapular exanthems (MPEs). Misclassification may easily lead to the wrong conclusion regarding diagnosis and manage- ment. This guideline focuses on the clinical manifestations of DHR which aid correct diagnostic classification. As recommended by the international consensus on drug allergy, we use the term DHR for objectively reproducible symptoms or signs initiated by exposure to a defined drug at a dose tolerated by a normal person that clinically resembles allergy, and we are focusing on cutaneous DHR (CDHR).1 Other terms used for CDHR nomenclature are explained in Table S1.

The guideline aims to assist all clinicians managing DHR by pro- viding the approach needed for doctors to correctly classify CDHR. Importantly, we have included precise definitions of CDHR, which we hope can become a standard tool for reference. Included in this guideline are criteria for when to think of DHR; an overview and a classification of CDHR; a detailed clinical description of morphologi- cal aspects in the skin; differences between urticaria and exanthems; differential diagnoses; how to distinguish between different forms of CDHR; danger signs; and important considerations for diagnosis and management. Another part of the guideline is aimed at patients to give a stan- dardized and better description of their skin manifestations as well as for important information to be given to the patient by the physi- cian. Finally, recommendations for audit points are included.
Read the whole Article: https://pubmed.ncbi.nlm.nih.gov/30028512/

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