Rifampicin-induced lichenoid drug eruption

Rifampicin is a bactericidal drug extensively used for tuberculosis and leprosy. Common adverse drug reactions of rifampicin are hepatotoxicity, flu-like syndrome, gastrointestinal symptoms and thrombocytopenia; cutaneous adverse reaction encountered in only ∼1.23% of cases.1 A 45-year-old man, recently diagnosed with sputum-positive pulmonary tuberculosis and started on continuation phase therapy with isoniazid and rifampicin (Cat 1) for preceding 1 month presented with 2-week history of acute onset, pruritic generalised skin eruptions. Physical examination revealed multiple, violaceous, discrete and coalescing papules and plaques distributed almost symmetrically over the scalp, face, trunk and extremities (figure 1A,B). Other mucocutaneous and systemic examination was unremarkable. Laboratory investigation was notable for peripheral eosinophilia (absolute eosinophil count 3.01 × 10ˆ9/L). Histopathological examination from lesion revealed hyperkeratosis with focal parakeratosis, basal cell degeneration with upper dermal band-like infiltrate comprising mononuclear cells and eosinophils, multiple colloid bodies in upper epidermis, melanin incontinence and sparse deep dermal perivascular infiltration, consistent with lichenoid drug eruption (LDE) (figure 1C). Isoniazid and rifampicin were stopped and the patient started on topical potent steroid and oral antihistaminic. Within 2 weeks, all skin lesions resolved and new lesions stopped appearing. Isoniazid and rifampicin were restarted sequentially with lower doses. However, on sequentially increasing the dose of rifampicin, new skin lesions reappeared over trunk when the daily dosage had reached 450 mg.