Fixed drug eruption: Contribution of patch tests

• Published in: Revue française d'allergologie (2009) 2023-04, Vol.63 (3), p.103533, Article 103533
• Main Authors: Charfi, O., Lakhoua, G., Zaiem, A., Kastalli, S., Hamza, I.S., Aouinti, I., El Aidli, S.
• Format: Article
• Language: English
• ISSN: 1877-0320; 1877-0320
• DOI: 10.1016/j.reval.2023.103533

Fixed drug eruption (FDE) is generally a non-severe drug eruption. Pharmacovigilance investigations usually succeed to identify the responsible drug, but in some cases, mainly in multiple drug intake or when patients forget drug names, patch tests (PT) can be useful. The aim of the work was to describe the epidemiological, clinical data of the patients and the results of the PTs. We conducted a retrospective study over a six-year period from January 2016 to December 2021 in the adverse effects collection and analysis department in the Tunisian Centre of Pharmacovigilance. This study included patients in whom the diagnosis of FDE was retained and who had an exploration by PT. Drug imputability was assessed using the French method. Our study involved 25 patients. Sex ratio M/F was 1.5. The age of the patients ranged from 11 to 68 years, with a median of 48 years. Mucosal involvement was noted in 13 patients. The suspect drugs were paracetamol or a nonsteroidal anti-inflammatory drug in 1/3 of the cases respectively. A total of 38 PTs was performed: 20 were negative, three doubtful and 15 positives. Thirteen drugs were tested. Paracetamol PTs were negative in nine/14 cases. The oral provocation test carried out in five patients was negative. Nonsteroidal anti-inflammatory drug were tested in 11 cases and were positive in eight cases among them six to mefenamic acid. In one patient, patch test induced a reactivation of all lesions. Regarding antibiotics, the 3 PT performed with metronidazole were positive. The 2 amoxicillin PTs were negative with a negative reintroduction test for one patient. Thus, the PTs helped to identify the culprit drug for the occurrence of FDE in 17 cases/25, to clear a drug in 8 cases/25 but did not make it possible to determine the responsible drug in seven cases. A prospective study including a larger number of patients could be considered to determine the sensitivity of PTs in FDE.