title: Eczematous-type multiple drug allergy from isoniazid and ethambutol with positive patch test results.
abstract: Multiple drug allergy (MDA) is characterized by hypersensitivity to 2 or more chemically unrelated drugs. Multiple drug allergy from simultaneous use of antituberculosis drugs is a rare phenomenon that mainly presents as an urticarial or maculopapular eruption. This case report describes a 58-year-old man who developed a generalized eczematous eruption during the sixth week of oral therapy with 4 antituberculosis drugs-isoniazid, ethambutol, rifampicin, and morphazinamide-for treatment of suspected pleural tuberculosis. The eruption resolved after treatment with systemic corticosteroids and cessation of isoniazid and ethambutol. During a lesion-free period 6 months after cessation of the corticosteroids, patch testing with serial dilutions of isoniazid and ethambutol revealed positive reactions; irritant patch test reactions were excluded by testing with graded concentrations of each drug. The patient avoided the causative drugs and reported no new eruptions at 1-year follow-up. It is important for dermatologists to consider the value of patch testing in determining the causative drugs in suspected cases of eczematous-type MDA.
authors.affiliation: Istanbul Üniversitesi Istanbul Tıp Fakültesi, Deri ve Zührevi Hastalıklar Anabilim Dalı, 34093 Istanbul, Turkey. profeo@istanbul.edu.tr.
authors.forename: Esen
authors.initials: E
authors.lastname: Özkaya
mesh_terms: D000995:Antitubercular Agents / Q000008:administration & dosage / Q000009:adverse effects* / Q000627:therapeutic use; D003875:Drug Eruptions / Q000175:diagnosis / Q000209:etiology* / Q000473:pathology; D004359:Drug Therapy, Combination; D004485:Eczema / Q000139:chemically induced / Q000175:diagnosis / Q000473:pathology; D004977:Ethambutol / Q000008:administration & dosage / Q000009:adverse effects* / Q000627:therapeutic use; D005500:Follow-Up Studies; D006801:Humans; D007538:Isoniazid / Q000008:administration & dosage / Q000009:adverse effects* / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D010328:Patch Tests; D011719:Pyrazines / Q000008:administration & dosage / Q000627:therapeutic use; D012293:Rifampin / Q000008:administration & dosage / Q000627:therapeutic use
chemical_list: D000995:Antitubercular Agents; D011719:Pyrazines; D004977:Ethambutol; C038993:morphazinamide; D007538:Isoniazid; D012293:Rifampin