Fixed drug eruption induced by an iodinated non-ionic X-ray contrast medium: a practical approach to identify the causative agent and to prevent its recurrence

Radiocontrast Media Hypersensitivity Reactions in Children

Hypersensitivity reactions to radiocontrast media seem to be rare in children. Furthermore, the use of radiocontrast media in children remains quite safe in terms of the severity of reactions. Since pediatric guidelines are lacking, the diagnostic workup employed in adults could be adapted to children, taking into account that results have not yet been validated in this age group. Specific protocols for risk stratification and management of severe reactions have been proposed so far.

The Role of Patch Testing in Evaluating Delayed Hypersensitivity Reactions to Medications

Confirming drug imputability is an important step in the management of cutaneous adverse drug reactions (CADR). Re-challenge is inconvenient and in many cases life threatening. We review the literature on ideal patch testing technique for specific CADRs. Testing should be performed approximately 3 months after the resolution of the eruption using standard patch testing techniques. Commercially available patch test preparations are available for a minority of drugs, so in most cases, testing should be performed with the drug at various recommended concentrations and in different vehicles. Testing to all known excipients, such as dyes, vehicles and preservatives is also important. Immunosuppressive medications should be discontinued or down titrated to the lowest tolerable dose to decrease the risk of false negative reactions. We provide an overview of expert recommendations and extant evidence on the utility of patch testing for identifying the culprit drug in common CADRs and for specific drug or drug classes. Overall, there appears to be significant variability in the patch test positivity of different drugs, which is likely the result of factors intrinsic to the drug such as dermal absorption (as a function of lipophilicity and molecular size) and whether the drug itself or a downstream metabolite is implicated in the immune reaction. Drugs with high patch test positivity rates include beta-lactam antibiotics, aromatic anticonvulsants, phenytoin, and corticosteroids, among others. Patch testing positivity varies both as a function of the drug and type of CADR. The sum of the evidence suggests that patch testing in the setting of morbilliform eruptions, fixed drug eruption, acute generalized exanthematous pustulosis, and possibly also drug-induced hypersensitivity syndrome, photoallergic and eczematous reactions may be worthwhile, although utility of testing may vary on the specific drug in question for the eruption. It appears to be of limited utility and is not recommended in the setting of other complex CADR, such as SJS/TEN and leukocytoclastic vasculitis.

Practice parameters for diagnosing and managing iodinated contrast media hypersensitivity

Immediate and nonimmediate hypersensitivity reactions to iodinated contrast media (ICM) have been reported to occur in a frequency of about 0.5%-3% of patients receiving nonionic ICM. The diagnosis and management of these patients vary among guidelines published by various national and international scientific societies, with recommendations ranging from avoidance or premedication to drug provocation test. This position paper aims to give recommendations for the management of patients with ICM hypersensitivity reactions and analyze controversies in this area. Skin tests are recommended as the initial step for diagnosing patients with immediate and nonimmediate hypersensitivity reactions; besides, they may also help guide on tolerability of alternatives. Re-exposition or drug provocation test should only be done with skin test-negative ICMs. The decision for performing either re-exposition or drug provocation test needs to be taken based on a risk-benefit analysis. The role of in vitro tests for diagnosis and pretreatment for preventing reactions remains controversial.

Contrast-induced generalized bullous fixed drug eruption resembling Stevens-Johnson syndrome

A 59-year-old woman with end-stage renal disease presented for suspected Stevens-Johnson syndrome that was ultimately diagnosed as generalized bullous fixed drug eruption (GBFDE) secondary to the administration of iodinated nonpolar radiocontrast. The patient had three previous episodes of a generalized bullous eruption after a thrombectomy, fistulogram, and an arteriovenous fistula revision, all requiring radiocontrast administration. Biopsies taken after previous eruptions demonstrated full-thickness epidermal necrosis, and she was diagnosed with Stevens-Johnson syndrome thought to be due to allopurinol. However, against medical advice she continued taking allopurinol and remained asymptomatic until the current presentation. Based on the clinical appearance and time frame of the eruptions, the patient was diagnosed with GBFDE due to radiocontrast. GBFDE, a rare variant of a fixed drug eruption, can be misdiagnosed as Stevens-Johnson syndrome due to their overlapping features of drug-induced whole-body blisters and variable degrees of epidermal necrosis.

Fixed Drug Eruption due to Iopromide (Ultravist®)

A 69-year-old male presented with several painful erythematous patches on both palms and trunk several days after receiving iopromide (Ultravist®, Shering, Berlin, Germany). A fixed drug eruption (FDE) due to iopromide was suspected clinically. However, at that time, the patch test with iopromide at the lesion site gave negative results. Three years later, the patient was mistakenly administered iopromide again and patches with vesicles recurred on the same sites as well as on the genitalia. This episode was repeated once again after 1 year. In all episodes, the skin lesion resolved after application of topical steroids. Although a patch test with iopromide was negative in our case, we made a diagnosis of FDE due to iopromide because the skin lesions occurred again at the previously involved area after re-exposure to iopromide. To date, only three cases of FDE caused by non-ionic monomers have been documented in the English literature. Herein, we report on an interesting case of FDE caused by iopromide.