Symmetric drug-related intertriginous and flexural exanthema: Clinicopathologic study of 19 cases and review of literature

Delayed drug hypersensitivity reactions: How p-i transforms pharmacology into immunology

Delayed drug hypersensitivity reactions (dDHRs) are iatrogenic diseases, which are mostly due to non-covalent interactions of a drug with the immune receptors HLA and/or TCR causing T-cell activation. This is also known as pharmacological interaction with immune receptors or p-i. P-i activation differs from classical antigen-driven immune reactions: a) drug binding induces structural changes in TCR-HLA proteins which make them look like allo-like TCR-HLA-complexes, able to elicit allo-like stimulations of T cells with cytotoxicity and IFNγ production, notably without the involvement of innate immunity; b) drug binding to TCR and/or HLA can increase the affinity of TCR-HLA interactions, which may affect signaling and IL-5 production by CD4+ T cells, and thus contribute to eosinophilia commonly found in dDHRs or induce oligoclonal T cell expansions; c) Both, antigen and p-i stimulations can induce eosinophil- or neutrophil-rich inflammations; but these stimulations should be distinguished as their underlying mechanism and development differ; and d) p-i stimulation can - like graft versus host reactions - result in long-lasting T-cell activations, which can lead to viremia, occasional autoimmunity, or a new syndrome characterized by multiple drug hypersensitivity (MDH). In summary, dDHRs are not allergic reactions but represent peculiar T-cell activations, similar to allo-like stimulations. Understanding and considering the p-i mechanism is needed for preventive measures and optimal treatments of dDHR. In addition, it may help to understand TCR signaling, alloreactivity, and may even open a new way of specific immune stimulations.

Symmetrical drug-related intertriginous and flexural exanthema (SDRIFE) after administration of corticosteroids: Case series and review of literature

BACKGROUND

Cutaneous manifestations of drug-induced type IV reactions vary widely, with symmetrical drug-related intertriginous and flexural exanthema (SDRIFE) being a less common presentation. Corticosteroids (CS), primarily known for their anti-inflammatory effects, rarely induce hypersensitivity reactions.

OBJECTIVE

The aim of this case series is to report four cases of SDRIFE following systemic prednisolone therapy and to review existing CS classification proposals to better understand cross-reactivity of CS.

PATIENTS/METHODS

Patients recruited at a German dermatology centre underwent allergologic evaluation including prick and patch testing with various CS. Positive cases underwent oral challenge testing with alternative agents. The classification systems of Coopman et al. and Baeck et al. were taken into account.

DISCUSSION

Despite a paucity of literature, CS-induced type IV reactions do occur, including SDRIFE. Classification systems based on chemical structure provide insight into cross-reactivity patterns. Provocation tests with alternative CS highlight the complexity of managing CS hypersensitivity.

CONCLUSION

SDRIFE may develop following systemic prednisolone therapy. Classification systems are helpful in understanding cross-reactivity and help in the selection of alternative preparations but are not always reliable. Individualised assessment is crucial for managing CS hypersensitivity, with consideration of alternative agents and emergency use of CS when necessary.

Characterization of T-Helper Immune Phenotype in Symmetrical Drug-Related Intertriginous and Flexural Exanthema (SDRIFE) Endorses a Delayed-Type Hypersensitivity Reaction

ABSTRACT

Symmetrical drug-related intertriginous and flexural exanthema (SDRIFE) is a cutaneous drug eruption with a characteristic distribution of erythema on the gluteal/inguinal region and intertriginous areas with unclear pathogenesis. In this study, we aimed to characterize the T-helper immune phenotype in SDRIFE in comparison with psoriasis and eczema to further the understanding of the pathophysiology and immune response of this rare disorder. Immunohistochemical staining was performed on 9 skin biopsies each from SDRIFE, psoriasis, and eczema using immunohistochemistry for CD3 and dual CD4/T-bet, CD4/GATA3, and CD4/RORC to quantify the percentage of Th1, Th2, and Th17 cells, respectively. A significant difference was detected in the average percentage of Th1 between all 3 groups with the highest percentage of Th1 cells seen in psoriasis, followed by SDRIFE and eczema. SDRIFE showed significantly lower Th2 expression as compared to both psoriasis and eczema. There was a trend towards a higher average percentage of Th17 in psoriasis and SDRIFE, and the ratio of Th17:Th2 was significantly higher in samples of SDRIFE compared with both eczema and psoriasis. The findings characterize SDRIFE as a Th1 and possibly Th17-driven process, which could inform future therapeutic options and substantiate the model of SDRIFE as a delayed-type hypersensitivity reaction.

Everolimus-induced Symmetrical Drug-related Intertriginous and Flexural Exanthema

Abstract is missing (Short communication)

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.

A flexural exanthem following postexposure prophylaxis

We report a case of symmetrical drug-related intertriginous and flexural exanthema following antiretroviral postexposure prophylactic medications, tenofovir and emtricitabine, commencement of which preceded the onset of the rash. Tenofovir and emtricitabine are both nucleoside reverse transcriptase inhibitor medications, commonly used to prevent development of AIDS.