Introduction: Lichen planus is an autoimmune inflammatory disease that can be associated with infections, drugs and vaccines. As concerning the potential triggering effect of vaccine, there is evidence a few cases of new-onset lichen planus that appeared after COVID vaccine, particularly the Pfizer/BioNTech vaccine. Case report: This report is a case of a newonset lichen planus triggered by the Pfizer/BioNTech vaccine administration in a healthy young female. Dermatological examination revealed polygonal, itchy, erythematous papules on trunk, upper and lower limbs, that coalesced into brownish plaques in the ankles, flexural wrist and knee. No mucosal involvement was noted. In view of the clinical picture, the timing of the skin eruption with respect to the vaccine and the histopathologic findings, a vaccine-induced lichen planus triggered by the COVID-19 vaccine has been diagnosed. Conclusion: Lichen planus or lichenoid-like eruption as a cutaneous manifestation following COVID-19 vaccines are rare, and the pathogenesis for its development is still unclear. Clinical trials showed that the leading vaccines upregulate Tcell response (Th1) and incrementing inflammatory cytokines involved in the pathogenesis of autoimmune diseases, such as lichen planus. Although we still do not completely understand its pathogenesis, dermatologists should be aware of the possibility and keep an eye out for worsening or debut of this disease after the COVID-19 vaccine. Vaccinated patients should be monitored for skin manifestations, and dermatological evaluation should be offered, when needed.

This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.