Reactive Inflammatory Erythemas

Abstract Annular erythemas may be classified as those due to a specific skin disorder such as psoriasis and tinea corporis or a cutaneous inflammatory reaction to a trigger such as a drug, infection or malignancy. In many cases the trigger for the reactive inflammatory erythemas remains elusive and these cases are then described as idiopathic. This chapter describes the known patterns of reactive inflammatory erythemas, namely erythema multiforme, annular erythema of infancy, necrolytic migratory erythema, erythema annulare centrifugum, erythema chronicum migrans, erythema gyratum repens and erythema marginatum. Overall, these reactive inflammatory erythemas are more common in children than adults but they can occur all ages. When assessing a patient with a reactive erythema, knowledge of local disease prevalence and local use of therapeutics will be useful. By inference, disease associations will be influenced by local population health and socioeconomic factors and will vary with geography and over time. Identifying relevant triggers are important to optimise patient care and prevent avoidable morbidity and mortality.