[Multiform exudative erythema caused by hydroxychloroquine, diagnosed by epicutaneous tests: A case report].

Introduction: Multiform exudative erythema is a rare delayed hypersensitivity reaction associated with medications. The manifestations caused by hydroxychloroquine are exceptional; however, due to the increase in its prescription due to the recent SARS-CoV-2 pandemic, adverse reactions have been exacerbated.

Case report: A 60-year-old female patient, who attended the Emergency Department for a picture of erythematous rash of one week of evolution, with involvement of the trunk, face and palms of the hands. Laboratory studies reported: leukocytosis with neutrophilia and lymphopenia, without eosinophilia or abnormal liver enzymes. The lesions continued to descend towards her extremities, with subsequent desquamation. She was prescribed prednisone 15 mg/24 h for three days, tapering to 10 mg/24 h, until her new assessment, in addition to antihistamines. Two days later, new macular lesions appeared in the presternal area and on the oral mucosa. Control laboratory studies did not show alterations. Skin biopsy reported: vacuolar interface dermatitis with spongiosis and parakeratosis, compatible with erythema multiforme. Epicutaneous tests were carried out with meloxicam and 30% hydroxychloroquine in water and vaseline, occluded for two days and interpreted at 48 and 96 hours, with a positive result for the latter. The diagnosis of multiform exudative erythema due to hydroxychloroquine was established.

Conclusions: This study confirms the efficacy of patch tests in patients with delayed hypersensitivity reactions to hydroxychloroquine.