Severe delayed hypersensitivity reactions to IL-1 and IL-6 inhibitors link to common HLA-DRB1*15 alleles.

OBJECTIVES: Drug reaction with eosinophilia and systemic symptoms (DRESS) is a severe, delayed hypersensitivity reaction (DHR). We observed DRESS to inhibitors of interleukin 1 (IL-1) or IL-6 in a small group of patients with Still's disease with atypical lung disease. We sought to characterise features of patients with Still's disease with DRESS compared with drug-tolerant Still's controls. We analysed human leucocyte antigen (HLA) alleles for association to inhibitor-related DHR, including in a small Kawasaki disease (KD) cohort. METHODS: In a case/control study, we collected a multicentre series of patients with Still's disease with features of inhibitor-related DRESS (n=66) and drug-tolerant Still's controls (n=65). We retrospectively analysed clinical data from all Still's subjects and typed 94/131 for HLA. European Still's-DRESS cases were ancestry matched to International Childhood Arthritis Genetics Consortium paediatric Still's cases (n=550) and compared for HLA allele frequencies. HLA association also was analysed using Still's-DRESS cases (n=64) compared with drug-tolerant Still's controls (n=30). KD subjects (n=19) were similarly studied. RESULTS: Still's-DRESS features included eosinophilia (89%), AST-ALT elevation (75%) and non-evanescent rash (95%; 88% involving face). Macrophage activation syndrome during treatment was frequent in Still's-DRESS (64%) versus drug-tolerant Still's (3%; p=1.2×10-14). We found striking enrichment for HLA-DRB1*15 haplotypes in Still's-DRESS cases versus INCHARGE Still's controls (p=7.5×10-13) and versus self-identified, ancestry-matched Still's controls (p=6.3×10-10). In the KD cohort, DRB1*15:01 was present only in those with suspected anakinra reactions. CONCLUSIONS: DRESS-type reactions occur among patients treated with IL-1/IL-6 inhibitors and strongly associate with common HLA-DRB1*15 haplotypes. Consideration of preprescription HLA typing and vigilance for serious reactions to these drugs are warranted.

Increased serum anti-CYP2E1 IgG autoantibody levels may be involved in the pathogenesis of occupational trichloroethylene hypersensitivity syndrome: a case-control study.

Occupational exposure to trichloroethylene (TCE) causes a systemic skin disorder with hepatitis known as TCE hypersensitivity syndrome (TCE-HS). Human Leukocyte Antigen (HLA)-B*13:01 is its susceptibility factor; however, the immunological pathogenesis of TCE-HS remains unknown. We herein examined the hypothesis that autoantibodies to CYP2E1 are primarily involved in TCE-HS. A case-control study of 80 TCE-HS patients, 186 TCE-tolerant controls (TCE-TC), and 71 TCE-nonexposed controls (TCE-nonEC) was conducted to measure their serum anti-CYP2E1 antibody (IgG) levels. The effects of TCE exposure indices, such as 8-h time-weighted-average (TWA) airborne concentrations, urinary metabolite concentrations, and TCE usage duration; sex; smoking and drinking habits; and alanine aminotransferase (ALT) levels on the antibody levels were also analyzed in the two control groups. There were significant differences in anti-CYP2E1 antibody levels among the three groups: TCE-TC > TCE-HS patients > TCE-nonEC. Antibody levels were not different between HLA-B*13:01 carriers and noncarriers in TCE-HS patients and TCE-TC. The serum CYP2E1 measurement suggested increased immunocomplex levels only in patients with TCE-HS. Multiple regression analysis for the two control groups showed that the antibody levels were significantly higher by the TCE exposure. Women had higher antibody levels than men; however, smoking, drinking, and ALT levels did not affect the anti-CYP2E1 antibody levels. Anti-CYP2E1 antibodies were elevated at concentrations lower than the TWA concentration of 2.5 ppm for TCE exposure. Since HLA-B*13:01 polymorphism was not involved in the autoantibody levels, the possible mechanism underlying the pathogenesis of TCE-HS is that TCE exposure induces anti-CYP2E1 autoantibody production, and HLA-B*13:01 is involved in the development of TCE-HS.

Current Perspective Regarding the Immunopathogenesis of Drug-Induced Hypersensitivity Syndrome/Drug Reaction with Eosinophilia and Systemic Symptoms (DIHS/DRESS).

Drug-induced hypersensitivity syndrome/drug reaction with eosinophilia and systemic symptoms (DIHS/DRESS) is a severe type of adverse drug eruption associated with multiorgan involvement and the reactivation of human herpesvirus 6, which arises after prolonged exposure to certain drugs. Typically, two waves of disease activity occur during the course of DIHS/DRESS; however, some patients experience multiple waves of exacerbation and remission of the disease. Severe complications, some of which are related to cytomegalovirus reactivation, can be fatal. DIHS/DRESS is distinct from other drug reactions, as it involves herpes virus reactivation and can lead to the subsequent development of autoimmune diseases. The association between herpesviruses and DIHS/DRESS is now well established, and DIHS/DRESS is considered to arise as a result of complex interactions between several herpesviruses and comprehensive immune responses, including drug-specific immune responses and antiviral immune responses, each of which may be mediated by distinct types of immune cells. It appears that both CD4 and CD8 T cells are involved in the pathogenesis of DIHS/DRESS but play distinct roles. CD4 T cells mainly initiate drug allergies in response to drug antigens, and then herpesvirus-specific CD8 T cells that target virus-infected cells emerge, resulting in tissue damage. Regulatory T-cell dynamics are also suggested to contribute to the diverse symptoms of DIHS/DRESS. However, the pathomechanisms of this complex disease remain largely unknown. In particular, how viral infections contribute to the pathogenesis of DIHS/DRESS and why autoimmune sequelae arise in DIHS/DRESS are yet to be elucidated. This review describes the clinical features of DIHS/DRESS, including the associated complications and sequelae, and discusses recent advances in our understanding of the immunopathogenic mechanisms of DIHS/DRESS.

Immunogenicity and skin clearance recapture in clinical studies of brodalumab.

BACKGROUND: Antidrug antibodies (ADAs) may change pharmacokinetic or pharmacodynamic profiles of biologic therapies, potentially decreasing efficacy. OBJECTIVE: To evaluate the potential effects of brodalumab immunogenicity on safety, efficacy, and retreatment. METHODS: Data from 1 phase 2 and 3 phase 3 studies of brodalumab in psoriasis were analyzed. RESULTS: Overall, 2.7% of patients had positive test results for binding ADAs after receiving brodalumab; ADAs were transient in 1.4% of patients, and there were no neutralizing ADAs. Among ADA-positive patients, 60.0% (3/5) achieved a static physician's global assessment score of 0 or 1 at week 12 in the group receiving the brodalumab 210 mg every 2 weeks, compared with 79.1% (1131/1429) of ADA-negative patients. All patients (100%) who experienced return of disease and were retreated with brodalumab 210 mg every 2 weeks (none were ADA positive) achieved at least a 75% improvement in Psoriasis Area And Severity Index, ≥90% of whom regained response by week 8 of retreatment. Hypersensitivity reactions were less frequent with brodalumab than with placebo. Injection site reactions occurred in 1.8% of patients treated with brodalumab versus 2% of patients treated with ustekinumab. LIMITATIONS: Retreatment could be assessed in only 1 phase 3 brodalumab study. CONCLUSION: Brodalumab compares favorably with other biologics in terms of immunogenicity and high rates of efficacy recapture upon retreatment.

Hypersensitivity to antibiotics in drug reaction with eosinophilia and systemic symptoms (DRESS) from other culprits.

BACKGROUND: Antibiotics have been implicated in the reactivation of exanthema and systemic involvement in drug reaction with eosinophilia and systemic symptoms (DRESS); however, it is not clear whether these patients become sensitized to the antibiotic. OBJECTIVE: To evaluate if, after DRESS, patients become sensitized to antibiotics. METHODS: We retrospectively reviewed the patch test (PT) data and clinical files of DRESS patients who were administered antibiotics during DRESS from other culprits. RESULTS: Nine patients out of 17 (53%) were positive to antibiotics in PT: six to the penicillin group and three to cephalosporins (including one patient with additional positivity to vancomycin). Considering the eight patients who were negative to antibiotics in PT, seven were exposed to a fluoroquinolone. Four cases were patch tested again and three remained positive to antibiotics 2 to 5 years thereafter. Two patients with positive PT results had an accidental re-exposure to antibiotics and developed a maculopapular exanthema without systemic symptoms. CONCLUSION: Exposure to antibiotics during DRESS or its prodromal phase could enhance sensitization to antibiotics, as confirmed by a positive PT. Reproducibility of positive PTs to antibiotics after several years and reactivation after re-exposure support that T-cell-mediated hypersensitivity to antibiotics in the setting of DRESS is a specific reaction.

HLA-A*32:01 is strongly associated with vancomycin-induced drug reaction with eosinophilia and systemic symptoms.

BACKGROUND: Vancomycin is a prevalent cause of the severe hypersensitivity syndrome drug reaction with eosinophilia and systemic symptoms (DRESS), which leads to significant morbidity and mortality and commonly occurs in the setting of combination antibiotic therapy, affecting future treatment choices. Variations in HLA class I in particular have been associated with serious T cell-mediated adverse drug reactions, which has led to preventive screening strategies for some drugs. OBJECTIVE: We sought to determine whether variation in the HLA region is associated with vancomycin-induced DRESS. METHODS: Probable vancomycin-induced DRESS cases were matched 1:2 with tolerant control subjects based on sex, race, and age by using BioVU, Vanderbilt's deidentified electronic health record database. Associations between DRESS and carriage of HLA class I and II alleles were assessed by means of conditional logistic regression. An extended sample set from BioVU was used to conduct a time-to-event analysis of those exposed to vancomycin with and without the identified HLA risk allele. RESULTS: Twenty-three subjects met the inclusion criteria for vancomycin-associated DRESS. Nineteen (82.6%) of 23 cases carried HLA-A*32:01 compared with 0 (0%) of 46 of the matched vancomycin-tolerant control subjects (P = 1 × 10-8) and 6.3% of the BioVU population (n = 54,249, P = 2 × 10-16). Time-to-event analysis of DRESS development during vancomycin treatment among the HLA-A*32:01-positive group indicated that 19.2% had DRESS and did so within 4 weeks. CONCLUSIONS: HLA-A*32:01 is strongly associated with vancomycin-induced DRESS in a population of predominantly European ancestry. HLA-A*32:01 testing could improve antibiotic safety, help implicate vancomycin as the causal drug, and preserve future treatment options with coadministered antibiotics.

Sensitivity and specificity of the lymphocyte transformation test in drug reaction with eosinophilia and systemic symptoms causality assessment.

BACKGROUND: Drug reaction with eosinophilia and systemic symptoms (DRESS) is a severe delayed hypersensitivity reaction. The determination of drug causality is complex. The lymphocyte transformation test (LTT) has been reported positive in more than 50% of DRESS cases. Nevertheless, the sensitivity and specificity of LTT specifically in DRESS have not yet been established. Rechallenge with the culprit drug is contraindicated and cannot be used as gold standard for sensitivity and specificity determination. OBJECTIVE: To estimate the sensitivity and specificity of LTT in a clinically defined series of patients with DRESS. METHODS: Some 41 patients diagnosed with DRESS were included in the study. The results of the algorithm of the Spanish Pharmacovigilance System were used as the standard for a correct diagnosis of drug causality. A standard LTT was performed with involved drugs in acute or recovery samples. A stimulation index (SI) ≥2 in at least one concentration except for beta-lactams (SI ≥3) and contrast media (SI ≥4) was considered positive. Contingency tables and ROC curves were used for analysis. RESULTS: Sensitivity and specificity of LTT in the recovery phase of DRESS were 73% and 82%, respectively, whereas in the acute phase, they were only 40% and 30%, respectively. Comparison of skin tests and LTT confirmed a higher sensitivity and specificity of LTT in DRESS. LTT showed high sensitivity (S) and specificity (Sp) for anticonvulsants (S 100%, Sp 100%; P = .008), anti-TB drugs (S 87.5%, Sp 100%; P = .004), and beta-lactams (S 73%, Sp 100%; P = .001). ROC curves revealed that the best criteria for LTT positivity for all drugs are SI ≥2 in at least one concentration, increasing overall sensitivity to 80%, and for beta-lactams from 73% to 92%. CONCLUSIONS AND CLINICAL RELEVANCE: LTT is a good diagnostic tool for drug causality in DRESS, mainly when performed in the recovery phase.

Th17 Response of Borderline-Lepromatous Leprosy Inhibits Rash Manifestation of Dapsone Hypersensitivity Syndrome: Case Report.

BACKGROUND: Dapsone hypersensitivity syndrome (DHS) is a rare, but potentially life-threatening reaction to dapsone. OBJECTIVE: Evaluation of immunological factors involved in the sparing of borderline-lepromatous (BL) leprosy patches by the severe exanthema related to DHS. METHODS: The authors describe a 19-year-old man with borderline-lepromatous leprosy with a recent diffuse rash, sparing only the hypochromic patches of leprosy, generalized lymphadenopathy, hepatomegaly, and jaundice 25 days after the start of multibacillary multidrug therapy. RESULTS: Laboratory testing was remarkable for leukocytosis with eosinophilia, atypical lymphocytosis, and elevated liver and canalicular enzymes. Immunohistopathology of the rash showed stronger expression of Th1 cytokines (IL1ß, TNFα, IFNγ, and iNOS), and limited expression of IL17, TGFb, IL4, and IL10. Whereas the hypochromic leprosy patches showed high expression of inflammatory cytokines IL1ß, TNFα, IFNγ, iNOS, and TGFß (Th1), and presented strong expression of IL17 and TGFß with no IL4 and IL10 expression, by the inflammatory infiltrate, characterizing a participation of Th17 response. CONCLUSION: Th17 response, coupled with the presence of subepidermal collagen band, seems to be directly related to the absence of DHS rash in these hypochromic leprosy patches.

T cell-mediated hypersensitivity reactions to drugs.

The immunological mechanisms driving delayed hypersensitivity reactions (HSRs) to drugs mediated by drug-reactive T lymphocytes are exemplified by several key examples and their human leukocyte antigen (HLA) associations: abacavir and HLA-B*57:01, carbamazepine and HLA-B*15:02, allo-purinol and HLA-B*58:01, and both amoxicillin-clavulanate and nevirapine with multiple class I and II alleles. For HLA-restricted drug HSRs, specific class I and/or II HLA alleles are necessary but not sufficient for tissue specificity and the clinical syndrome. Several models have been proposed to explain the immunopathogenesis of severe T cell-mediated drug HSRs, and our increased understanding of the risk factors and mechanisms involved in the development of these reactions will further the development of sensitive and specific strategies for preclinical screening that will lead to safer and more cost-effective drug design.

Association of HLA-B*15:13 and HLA-B*15:02 with phenytoin-induced severe cutaneous adverse reactions in a Malay population.

Phenytoin (PHT) is a common cause of severe cutaneous adverse reactions (SCARs), including Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN) and drug reaction with eosinophilia and systemic symptoms (DRESS). Although HLA-B*15:02 is associated with PHT-induced SJS/TEN (PHT-SJS/TEN) in Han Chinese and Thais, the genetic basis for susceptibility to PHT-induced SCARs (PHT-SCAR) in other populations remains unclear. We performed a case-control association study by genotyping the human leukocyte antigen (HLA)-B alleles of 16 Malay PHT-SCAR patients (13 SJS/TEN and 3 DRESS), 32 PHT-tolerant controls and 300 healthy ethnicity-matched controls. A novel genetic biomarker, HLA-B*15:13, showed significant association with PHT-SJS/TEN (53.8%, 7/13 cases) (odds ratio (OR) 11.28, P=0.003) and PHT-DRESS (100%, 3/3 cases) (OR 59.00, P=0.003) when compared with PHT-tolerant controls (9.4%, 3/32 controls). We also confirmed HLA-B*15:02 association with PHT-SJS/TEN (61.5%, 8/13 cases vs 21.9%, 7/32 controls; OR 5.71, P=0.016) when compared with PHT-tolerant controls. These alleles may serve as markers to predict PHT-SCAR in Malays.

Drug-specific CD4+ T-cell immune responses are responsible for antituberculosis drug-induced maculopapular exanthema and drug reaction with eosinophilia and systemic symptoms syndrome.

BACKGROUND: A multidrug regimen including isoniazid, rifampicin, pyrazinamide and ethambutol is commonly used as first-line treatment for tuberculosis. However, this regimen can occasionally result in severe adverse drug reactions, such as drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome and drug-induced liver injury. The culprit drug and mechanistic basis for the hypersensitive reaction are unknown. OBJECTIVES: To investigate drug-specific T-cell responses in patients with antituberculosis drug (ATD)-induced cutaneous hypersensitivity and its underlying mechanism. METHODS: We enrolled eight patients with ATD-induced maculopapular exanthema and DRESS and performed a lymphocyte transformation test. Subsequently, drug-specific T-cell clones were generated from four of the patients who showed proliferation in response to ATDs. We measured the drug-specific proliferative responses and counted the drug-specific interferon (IFN)-γ/granzyme B-producing cells after drug stimulation. Antihuman leukocyte antigen (HLA) class I and class II blocking antibodies were used to analyse human leukocyte antigen-restricted T-cell responses. RESULTS: Positive proliferative responses to ATDs were mostly found in patients with cutaneous hypersensitivity. Furthermore, we isolated isoniazid/rifampicin-specific T cells from patients, which consisted primarily of CD4+ T cells. Drug-specific CD4+ T cells proliferated and secreted IFN-γ/granzyme B when stimulated with isoniazid or rifampicin, respectively. Isoniazid-responsive T-cell clones did not proliferate in the presence of rifampicin and vice versa. Drug-specific T-cell responses were blocked in the presence of anti-HLA class II antibodies. CONCLUSIONS: This study identifies the presence of isoniazid/rifampicin-specific T cells in patients with ATD-induced maculopapular exanthema and DRESS. Furthermore, it highlights the important role of drug-specific T-cell immune responses in the pathogenesis of these reactions.

Skin-Homing IL-13-Producing T Cells Expand in the Circulation of Patients with Drug Rash with Eosinophilia and Systemic Symptoms.

BACKGROUND: Drug rash with eosinophilia and systemic symptoms (DRESS), also known as drug-induced hypersensitivity syndrome, is characterized by severe drug-induced reactions with extensive cutaneous lesions and visceral involvement. Although T cell-mediated hypersensitivity reactions to drugs may be involved in the pathogenesis of DRESS, there is limited data regarding the T-cell phenotypes responsible for the pathogenesis of DRESS. OBJECTIVE AND METHODS: Using flow cytometry, we investigated the cytokine profiles and cutaneous lymphocyte antigen (CLA) expression in circulating T cells in patients with DRESS. RESULTS: The proportions of circulating IL-4- and IL-13-producing CD4+ T cells, but not CD8+ T cells, were significantly higher in patients with DRESS during the active stage of the disease than in healthy subjects, and these proportions declined during the recovery stage. No differences in the proportions of circulating IFN-γ-, IL-17-, and IL-22-producing CD4+ and CD8+ T cells were observed between patients with DRESS and healthy subjects. A strong correlation between the proportion of IL-13-producing CD4+ T cells and serum levels of thymus and activation-regulated chemokine was observed. The proportion of CLA-expressing CD4+ T cells was significantly higher during the active stage of the disease. Moreover, the proportion of IL-13-producing CD4+ T cells was higher in the CLA+ subset than in the CLA- subset. CONCLUSIONS: Skin-homing IL-13-producing CD4+ T cells may be involved in the pathogenesis of DRESS.

The immune response in trichloroethylene hypersensitivity syndrome: A review.

Trichloroethylene (TCE) has been used for a variety of industrial and consumer cleaning purposes because of its ability to dissolve organic substances. The multisystem injuries include those of skin, liver, and kidney, which are defined as TCE hypersensitivity syndrome (THS). THS is a serious occupational health issue. However, the mechanism of immune dysfunction leading to organ injury is poorly understood. Many studies reveal that skin lesions and organ injury caused by TCE are consistent with type IV hypersensitivity, also called delayed hypersensitivity, mediated by T cells. However, many researchers found T cell-mediated type IV hypersensitivity could not account for the pathogenesis of THS fully. Humoral immunity, including immunoglobulins and complement activation, may also play a possible role in THS pathogenesis. This review will describe the history, current understanding, and future research directions of the mechanism of THS.

Serological evidence that activation of ubiquitous human herpesvirus-6 (HHV-6) plays a role in chronic idiopathic/spontaneous urticaria (CIU).

Acute infection with viral pathogens in the herpesviridae family can trigger acute urticaria, and reactivation of herpesviridae is associated with cutaneous urticarial-like syndromes such as drug-induced hypersensitivity syndrome/drug reaction with eosinophilia and systemic symptoms (DRESS). Reactivation of latent herpesviridae has not been studied systematically in chronic idiopathic/spontaneous urticaria (CIU). This review proposes that CIU is an inflammatory disorder with autoimmune features (termed 'CVU' for chronic viral urticaria), based on serology consistent with the hypothesis that reactivation of a latent herpesvirus or -viruses may play a role in CIU. Serology obtained from a cohort of omalizumab (Xolair)-dependent patients with severe CIU was consistent with previous HHV-6 infection, persistent viral gene expression and replication. CIU patients also exhibited serological evidence of increased immune response to HHV-4 (Epstein-Barr virus, or EBV) but not all CIU patients were infected with EBV. These observations, combined with case reports of CIU response to anti-viral therapy, suggest that HHV-6, possibly interacting with HHV-4 in cutaneous tissues, is a candidate for further prospective study as a co-factor in CIU.

HLA and Delayed Drug-Induced Hypersensitivity.

Delayed drug allergy reactions (DDAR) are potentially fatal. Certain human leukocyte antigen (HLA) alleles have been associated with delayed allergy reactions following the administration of particular drugs. Examples are HLA-B*57:01 (abacavir), HLA-B*15:02/HLA-A*31:01 (carbamazepine), and HLA-B*58:01 (allopurinol). Based on the identification of these associations, it may now be possible to prevent certain allergy reactions that were, until recently, considered unpredictable. In this review, we will focus on the pharmacogenetics of the best-studied associations between specific HLA alleles and delayed allergy reactions and describe the pathogenesis models proposed so far. Finally, we will evaluate the genetic screening strategies available and discuss the clinical relevance of a better understanding of the immunogenetics and mechanisms involved in DDAR.

Longitudinal analysis of antibody profiles against plakins in severe drug eruptions: emphasis on correlation with tissue damage in drug-induced hypersensitivity syndrome and drug reaction with eosinophilia and systemic symptoms.

BACKGROUND: The evidence for severe drug eruption as a trigger for autoimmune disease has recently increased. No information is available on how tissue damage in severe drug eruptions can induce autoimmune responses. OBJECTIVES: To investigate whether the generation of autoantibodies (autoAbs) against plakin family proteins could be the cause or result of tissue damage in patients with severe drug eruptions and whether the generation of autoAbs could be prevented by systemic corticosteroids during the acute stage. METHODS: We retrospectively analysed alterations of serum levels of autoAbs against plakin family proteins in patients with Stevens-Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN) and drug-induced hypersensitivity syndrome (DiHS)/drug reaction with eosinophilia and systemic symptoms (DRESS) during the acute stage and long after resolution over a period of more than 10 years. RESULTS: AutoAbs against plakin family proteins were detected in patients with either SJS/TEN or DiHS/DRESS regardless of the epidermal damage in the acute stage, and were sustained even long after resolution in DiHS/DRESS, indicating that those autoAbs are neither the cause nor the consequence of epidermal damage, at least in DiHS/DRESS. Severe liver damage and noncorticosteroid therapy during the early and acute stages of DiHS/DRESS were associated with the subsequent generation of these autoAbs. CONCLUSIONS: These autoAbs are neither necessarily the cause nor the result of epidermal damage in DiHS/DRESS, because the presence of these autoAbs was not restricted to patients with SJS/TEN but was also observed in those with DiHS/DRESS, which is characterized by lack of epidermal damage. Severe liver damage and/or immune responses that could be prevented by corticosteroids in the acute stage of DiHS/DRESS are among the causal factors contributing to the generation of autoimmune responses.

Intralymphatic CD30+ T-cell proliferation during DRESS: a mimic of intravascular lymphoma.

INTRODUCTION: We describe the case of a patient presenting with drug rash with eosinophilia and systemic symptoms (DRESS), where cutaneous biopsy revealed intravascular atypical lymphocytes suggestive of lymphoma. CASE REPORT: A 77-year-old man was treated with antibiotics for a hip prosthesis infection. Eight weeks later, he developed a maculo-papulous eruption, edema of the extremities, fever and blood eosinophilia. Cutaneous biopsy revealed an atypical T-cell proliferation into the dermal lymphatic vessels. The lymphocytes were mid-sized, with mitoses and apoptotic figures. They were CD3+, CD4+, CD5+ and some were CD30+. There was no T-cell receptor (TcR) clonal rearrangement. Complete regression of cutaneous eruption and eosinophilia was observed after ceasing treatment with antibiotics. The diagnosis was that of a benign atypical intralymphatic T-cell proliferation associated with DRESS. DISCUSSION: The occurrence of atypical dermal CD30+ T-cells in cutaneous biopsy during benign reactive conditions such as arthropod bites or scabies is well-known. The intralymphatic localization of such atypical reactive lymphocytes is much less common and represents a diagnostic pitfall because it can suggest aggressive intravascular lymphoma. CONCLUSION: We report the first case of benign atypical intralymphatic CD30+ T-cell proliferation associated with DRESS. Diagnostic clues include immunohistochemistry, absence of TcR clonal rearrangement, and anatomo-clinical correlation.