Drug-induced exanthems: Correlation of allergy testing with histologic diagnosis

Pregabalin-induced delayed cutaneous hypersensitivity reaction occurring after 40 days of use: a case report

Pregabalin is the first-line treatment for neuropathic pain. Cases of cutaneous hypersensitivity reactions caused by pregabalin generally occur within 2 weeks of initiating medication. We report a rare case of a delayed cutaneous hypersensitivity reaction caused by pregabalin, which was confirmed by a drug provocation test. A 72-year-old man with severe herpes zoster neuralgia developed maculopapular drug eruption covering 80% to 90% of his total body surface area after 40 days of combined multidrug analgesia. A drug provocation test for pregabalin was positive. The time interval between initiating medication and the onset of the patient's rash was the longest and he also had the largest area of skin affected compared with patients with a similar condition in previous related reports. Remaining vigilant for possible adverse cutaneous hypersensitivity reactions during treatment is important because of the long-term course of pregabalin treatment for neuropathic pain.

Development of a clinical algorithm to predict phenotypic switches between atopic dermatitis and psoriasis (the "Flip-Flop" phenomenon)

BACKGROUND

Atopic dermatitis (AD) and psoriasis vulgaris (PV) are almost mutually exclusive diseases with different immune polarizations, mechanisms and therapeutic targets. Switches to the other disease ("Flip-Flop" [FF] phenomenon) can occur with or without systemic treatment and are often referred to as paradoxical reactions under biological therapy.

METHODS

The objective was to develop a diagnostic algorithm by combining clinical criteria of AD and PV to identify FF patients. The algorithm was prospectively validated in patients enrolled in the CK-CARE registry in Bonn, Germany. Afterward, algorithm refinements were implemented based on machine learning.

RESULTS

Three hundred adult Caucasian patients were included in the validation study (n = 238 with AD, n = 49 with PV, n = 13 with FF; mean age 41.2 years; n = 161 [53.7%] female). The total FF scores of the PV and AD groups differed significantly from the FF group in the validation data (p < .001). The predictive mean generalized Youden-Index of the initial model was 78.9% [95% confidence interval 72.0%-85.6%] and the accuracy was 89.7%. Disease group-specific sensitivity was 100% (FF), 95.0% (AD), and 61.2% (PV). The specificity was 89.2% (FF), 100% (AD), and 100% (PV), respectively.

CONCLUSION

The FF algorithm represents the first validated tool to identify FF patients.

The Frequency and Utility of Drug Cessation Trials in Older Adults With Chronic Eczematous Dermatitis of Unknown Etiology: A Retrospective Cohort Study

Background: Eczematous dermatitis is a major cause of recalcitrant pruritic eruptions in older adults. Although some medications have been implicated, there are limited data demonstrating the utility of medication changes. Objective: To investigate the utility and possible harms of drug cessation trials (DCTs) in chronic eczematous eruptions in the aging (CEEA). Methods: This is a retrospective cohort study utilizing electronic health records of DCTs in adults older than 65 years with CEEA. Results: We identified 646 patients >65 years with new onset eczematous eruptions, 89 (14%) of whom had no identifiable etiology. In this cohort, 35 patients underwent a total of 40 DCTs. Although there was mention of improvement in 17.5% (7/40), all patients sought tertiary care for their persistent rash. Negative outcomes occurred in 45% (18/40), all of which were due to exacerbation of a comorbidity that the medication was prescribed to treat. Conclusion: Our experience suggests that patients with CEEA undergo DCTs that do not improve their dermatitis and can lead to dangerous worsening of underlying conditions. Further study of the etiology of CEEA is needed.

Drug-Induced vs. Viral Maculopapular Exanthem—Resolving the Dilemma

Maculopapular exanthem is a commonly encountered presentation in routine clinical practice, and differentiation between its two most common etiologies, i.e., viral- and drug-induced, often poses a diagnostic dilemma. Clinical, hematological and biochemical investigations are seldom reliable in distinguishing between a drug reaction and a viral exanthem. Certain key histopathological features such as the presence of a moderate degree of spongiosis, extensive basal cell damage with multiple necrotic keratinocytes and dermal infiltrate rich in eosinophils or lymphocytes and histiocytes may favor a drug exanthem, while distinctive epidermal cytopathic changes and lymphocytic vasculitis point towards a viral etiology. Similarly, notable immunohistochemical markers such as IL-5, eotaxin and FAS ligand may support a diagnosis of a drug-induced maculopapular eruption. Histopathological and immunohistochemical evaluations may help in distinguishing between the two etiologies when faced with a clinical overlap, especially in patients on multiple essential drugs when drug withdrawal and rechallenge is not feasible.

[Immunopathology of cutaneous drug eruptions]

BACKGROUND

Adverse drug reactions (ADR) are common and may present clinically and histologically in a very heterogeneous manner. The pathophysiological understanding about causal immunological and non-immunological events has developed significantly over the past years. Skin and mucosa are commonly affected and are prone for histopathological examination. Certain groups of drugs such as immune checkpoint inhibitors may cause specific adverse reactions.

OBJECTIVES

To provide a comprehensive overview of the complex immunological events and the most common dermatohistopathological findings of cutaneous adverse drug reactions.

MATERIAL AND METHODS

Review of the literature (PubMed), own study data and pictures obtained via routine diagnostics at the University of Bonn.

RESULTS AND DISCUSSION

Drugs may induce a wide range of skin reactions displaying a diversity of cutaneous inflammatory patterns. Histopathological clues for drug eruptions may be: eosinophils, lichenoid infiltrate and isolated keratinocytic apoptosis; a thorough medical history and correlation of clinical findings and dermatohistopathology are most important. Knowledge of typical adverse reactions to checkpoint inhibitors and their management is of great clinical interest as their use is rising steadily.

A pilot study evaluating biomarker development for drug-induced chronic eczematous eruptions of aging individuals

Background

Identifying the drug(s) responsible for drug-induced chronic eczematous eruptions of aging individuals (CEEA) is a clinical challenge in patients on multiple medications. Reliable in vitro testing methods and biomarkers are needed to identify the causative agent and allow simultaneous assessment of T-cell responses to multiple drugs being taken concurrently. This study examined the feasibility of using in vitro, drug-specific T cell activation responses as a biomarker for drug-induced CEEA.

Methods

This was a single center, proof-of-concept pilot study at the University of Utah Hospital, Salt Lake City, Utah. Eight aging study subjects having a history suggestive of chronic eczematous drug eruptions suspected to have resulted from calcium channel blocker (CCB) and/or hydrochlorothiazide (HCTZ) hypersensitivity plus three matched aging control subjects were identified. Drug patch testing for CCB and/or HCTZ, in vitro drug antigen-induced lymphocyte proliferation assays, and multianalyte-determined cytokine release assays were performed before and after HCTZ and/or CCB incubation.

Results

All study and control subject blood samples tested failed to demonstrate detectable enhanced lymphocyte proliferation or cytokine release to in vitro CCBs or HCTZ challenge when tested with a fairly wide range of drug concentrations. Additionally, none of the enrolled patients developed a positive patch test to CCBs and/or HCTZ.

Conclusions

This pilot study aimed to correlate in vitro drug-induced T lymphocyte transformation and cytokine production with the presence of drug-induced CEEA. Failure to identify T cell proliferative responses to CCB drug antigens in our in vitro studies could have, in part, resulted from a pharmacologic inhibiting effect of CCB on T cell activation.

Eosinophilic Drug Allergy

While peripheral or tissue eosinophilia may certainly characterize drug eruptions, this feature is hardly pathognomonic for a medication-induced etiology. While delayed drug hypersensitivity reactions with prominent eosinophilic recruitment have been typically classified as type IVb reactions, their pathophysiology is now known to be more complex. Eosinophilic drug reactions have a diversity of presentations and may be benign and self-limited to severe and life-threatening. The extent of clinical involvement is also heterogeneous, ranging from isolated peripheral eosinophilia or single organ involvement (most often the skin and lung) to systemic disease affecting multiple organs, classically exemplified by drug-reaction with eosinophilia and systemic symptoms (DRESS). The spectrum of implicated medications in the causation of DRESS is ever expanding, and multiple factors including drug metabolites, specific HLA alleles, herpes viruses, and immune system activation have been implicated in pathogenesis. Due to this complex interplay of various factors, diagnostic workup in terms of skin and laboratory testing has not been validated. Similarly, the lack of controlled trials limits treatment options. This review also describes other localized as well as systemic manifestations of eosinophilic disease induced by various medication classes, including their individual pathophysiology, diagnosis, and management. Given the multitude of clinical patterns associated with eosinophilic drug allergy, the diagnosis can be challenging. Considerable deficits in our knowledge of these presentations remain, but the potential for severe reactions should be borne in mind in order to facilitate diagnosis and institute appropriate management.

Aminopenicillin-associated exanthem: lymphocyte transformation testing revisited

BACKGROUND

The lymphocyte transformation test (LTT) has been promoted as in-vitro test for diagnosis of drug hypersensitivity. For determination of statistical LTT sensitivity, series of patients with clinically uniform reactions followed by complete drug hypersensitivity work-up are mandatory. Assessment of LTT specificity requires control patients who tolerated exposure to the drug studied.

OBJECTIVE

To prospectively determine the diagnostic value of the LTT in a clinically and diagnostically well-defined series of patients.

METHODS

Patients with exanthematous skin eruptions after ampicillin (AMP) intake were included in this study. After exclusion or confirmation of delayed-onset allergic AMP hypersensitivity by skin and provocation testing, two independent LTTs were performed: one standard LTT and a modified LTT with additional anti-CD3/anti-CD28 monoclonal antibody stimulation.

RESULTS

By testing, delayed-onset allergic AMP hypersensitivity was diagnosed in 11 patients and definitely ruled out in 26. The standard LTT reached a diagnostic sensitivity of 54.5% while the modified LTT yielded 72.7%. However, the methodical test modification resulted in a decline of specificity from 92.3% (standard LTT) to 76.9%.

CONCLUSIONS AND CLINICAL RELEVANCE

In cases of AMP-associated exanthems, the diagnostic value of the LTT compared with routine allergy testing is limited. When evaluating such exanthems, provocation testing remains the gold standard. Delayed reading of intradermal skin tests remains most useful to avoid positive provocation reactions.