Lichenoid drug reactions: A retrospective clinical, epidemiological, and histopathological study of 55 cases

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Abstract Background: Drug-induced lichen planus is a relatively rare cutaneous drug adverse effect of several drugs presenting with pruritic, violaceous to hyperpigmented, and flat-topped papules and plaques with either generalized or localized distribution. Several drugs are known to cause it and have a variable latent period even for the same drug. Objectives: 1. To study the epidemiology and clinical presentation of lichenoid drug eruption. 2. To study the causative drugs and their latent period. 3. To study the histopathological findings. Materials and Methods: We conducted a retrospective study wherein 55 biopsy-proven cases of lichenoid drug eruption from May 2020 to May 2021 were studied for their age and sex distribution, clinical features, examination findings, and causative drugs and their latent period, and the histopathological findings were analyzed. Results: Out of the 55 patients, 33 were males and 22 were females, with an average age being 51 years. The most common causative drug was anti-tuberculosis therapy with a latent period ranging from 1 month to 7 months. Others were oral hypoglycemic agents such as gliptins, anti-retroviral therapy drugs, carbamazepine, NSAID, and rare being beta-HCG and chemotherapeutic agents. A total of 25.45% patients had a localized involvement, and the remaining were generalized. A total of 23.63% had mucosal involvement, and 21.81% had palms and soles involved. The most common histopathological findings were parakeratosis and acanthosis with lichenoid band of lymphocytic infiltrate with moderate presence of eosinophils. Conclusion: Considering the variable presentations of lichenoid drug eruption and the several drugs causing it, it becomes necessary to diagnose it early, differentiate it from idiopathic lichen planus, and decide about the continuation of the drug depending upon the risk-benefit ratio.