Acute localized exanthematous pustulosis (ALEP) induced by iomeprol (Iomeron 350): A diagnostic challenge

Rare delayed hypersensitivity reactions to contrast media: Severe cutaneous adverse reactions

The risk of developing a severe delayed cutaneous reaction (SCAR) is very low following iodine-based contrast medium (ICM) administration and extremely low following gadolinium-based contrast agent (GBCA) administration. However, SCAR can be very severe and potentially life-threatening. It is crucial for the imaging physician to recognize danger signals: bullous skin eruption, skin erosion and detachment, mucosal involvement, systemic symptoms, and laboratory abnormalities. Patients suspected of having a SCAR should be urgently referred to a drug allergy specialist or dermatologist. To prevent recurrence, consider exploring alternative imaging modalities and avoid administering the same type of contrast medium involved: if the culprit is a ICM, avoid all ICM and if the culprit is a GBCA, avoid all GBCA. In an allergy centre with experience in SCAR evaluation a careful allergologic analysis may be performed safely several months after the patient has recovered from SCAR. However, allergologic analysis is challenging due to the lack of reliable in vitro diagnostic tests and the risks of in vivo diagnostic tests, particularly drug provocation tests.

Results of patch testing in Acute generalized exanthematous pustulosis (AGEP): a literature review

The literature on positive patch test results in acute generalized exanthematous pustulosis (AGEP) is reviewed. 93 drugs were identified that have together caused 259 positive patch tests in 248 patients suffering from AGEP. The drug classes causing the highest number of reactions are beta-lactam antibiotics (25.9%), other antibiotics (20.8%), iodinated contrast media (7.3%) and corticosteroids (5.4%), together accounting for nearly 60% of all reactions. The highest number of reactions to individual drugs was to amoxicillin (n=36), followed by pristinamycin (n=25), diltiazem (n=14), amoxicillin-clavulanic acid (n=13), clindamycin (n=11) and iomeprol (n=8); 59 of the 93 drugs each caused a single case only. The "Top-10" drugs together caused over 50% of all reactions. The sensitivity of patch testing (percentage of positive reactions) in patients with AGEP is largely unknown, but may generally be around 50%, which also applies to pristinamycin. Patch testing in AGEP appears to be safe, although mild recurrence of AGEP skin symptoms or other rashes may occur occasionally. Clinical aspects of AGEP, including epidemiology, etiology and pathophysiology, clinical features, histology, treatment, and prognosis are briefly presented, as are diagnosing the disease and identifying the culprit drugs with patch tests, intradermal tests, in vitro tests, and challenge tests. This article is protected by copyright. All rights reserved.