Facial pustules due to drug-induced hypersensitivity syndrome/drug reaction with eosinophilia and systemic symptoms may histopathologically mimic eosinophilic pustular folliculitis: A case report

Recent advances in the diagnosis and treatment of DIHS/DRESS in 2025

Drug-induced hypersensitivity syndrome (DIHS) or drug reaction with eosinophilia and systemic symptoms (DRESS) is a severe drug reaction characterized by a range of clinical manifestations. These range from mild cases resolving upon cessation of the causative drug to severe cases involving complex disease progression and potential fatality. A hallmark of DIHS/DRESS is the sequential reactivation of herpesviruses, particularly human herpesvirus 6 (HHV-6), during the disease course, contributing to recurrent symptoms. Viral reactivation can lead to critical complications, including infectious DIHS/DRESS-associated complications (iDACs) and autoimmune sequelae (aDACs). Managing DIHS/DRESS remains challenging due to its complexity, requiring precise prediction and tailored treatment strategies. Recent studies suggest that early-stage classification using the DIHS/DRESS Severity (DDS) score may help identify refractory cases, including DACs. Furthermore, early intervention with anti-cytomegalovirus (anti-CMV) therapy can mitigate iDACs caused by CMV reactivation, preventing progression to severe CMV-related diseases. Long-term follow-up is crucial, as aDACs can manifest even 3 years postonset. Serial monitoring is recommended, particularly in patients treated with intravenous immunoglobulin or corticosteroid pulse therapy, which are recognized risk factors for aDAC development. This review highlights DIHS/DRESS management strategies, focusing on its clinical features, the role of viral reactivation, and therapeutic interventions.

The role of eosinophils in the differential diagnosis of inflammatory skin diseases

Eosinophils are known to be present in inflammatory skin diseases, but their diagnostic utility is not well established. Upon review of the published status of lesional eosinophils, several categories were identified. 1) Lesional eosinophils highly characteristic such that, in their absence, the pathologist may question the diagnosis. These include arthropod bite reactions and scabies, urticarial dermatitis, and other eosinophilic dermatoses. 2) Lesional eosinophils rare or absent, such that, in their presence, the pathologist may question the diagnosis. These include pityriasis lichenoides, graft versus host disease, and connective tissue disorders. 3) Lesional eosinophils variable and, while in some cases expected, are not required for diagnosis. These include drug reactions, atopic dermatitis and allergic contact dermatitis. 4) Lesional eosinophils variable and not expected but may be seen to a limited extent. These include lichen planus and psoriasis.