ABSTRACT
INTRODUCTION: Lichenoid cutaneous reactions to antituberculosis drugs are rare. Herein we report a new case. PATIENTS AND METHODS: A 41-year-old patient was seen for a profuse and pruriginous rash occurring 2 weeks after administration of rifampicin and isoniazid for pulmonary tuberculosis. Dermatological examination revealed polymorphic erythemato-squamous plaques with lichenoid, psoriatic and eczematous features, associated with cheilitis, erosions on the cheeks and diffuse onychodystrophy. The skin biopsy confirmed a lichenoid reaction. The pharmacovigilance investigation incriminated isoniazid and rifampicin. The patient was treated with topical corticosteroids and UVB phototherapy. The outcome involved complete regression of the eruption but with secondary anonychia. DISCUSSION: Antituberculosis drugs including isoniazid and rifampicin are known to induce lichenoid reactions. It is difficult to distinguish the results from lichen planus. The clinical polymorphism of the rash as well as the patient's drug intake militate in favour of a diagnosis of lichenoid reaction. Widespread ungual involvement, which is extremely rare, warranted early management in order to avert irreversible anonychia.
