Lichenoid drug eruption in patients on antitubercular therapy – a case series and literature reviews

Background. The spectrum of cutaneous adverse drug reactions (ADR) caused by antitubercular drugs is broad and includes Stevens‑Johnson syndrome, DRESS syndrome, and generalized lichenoid drug eruption (LDE). LDE accounts for less than 10% of all anti‑tubercular drug-induced cutaneous ADR. It is characterized by erythematous, violaceous papules resembling lichen planus. This can pose challenges regarding patient compliance and treatment effectiveness. Case report. The present case study describe 5 patients who developed lichenoid drug eruptions secondary to antitubercular therapy (ATT) at our outpatient department between March 2024 and February 2025. All cases occurred in women, suggesting a possible gender-specific susceptibility that warrants further investigation. Skin biopsies revealed histopathological features of lichenoid interface dermatitis, including eosinophils and necrotic keratinocytes. A systematic drug rechallenge identified pyrazinamide as the culprit in both tested patients, consistent with recent evidence indicating pyrazinamide as the most common cause of positive ATT rechallenge reactions. Conclusion. The exclusive female involvement and the definitive identification of pyrazinamide as the offending agent provide valuable clinical insights for the monitoring and management of ATT-induced LDE. Current treatment strategies emphasize continuation of essential ATT, whenever feasible, in combination with topical corticosteroids and antihistamines, while systematic rechallenge remains the gold standard for identifying causative drugs. Further research is needed to identify potential biomarkers that could enable earlier detection and management of ATT-induced LDE.