Lichen planus following COVID-19 vaccination: a narrative review.

Lichen planus (LP) is an inflammatory disease that afflicts the skin, mucous membranes and cutaneous appendages. Moreover, LP represents a prototype of lichenoid dermatosis, being characterized by the presence of a dense dermal cell infiltrate. Although most cases of LP are idiopathic, infectious and drug-related factors must also be considered in the aetiology. In this context, the occurrence of LP and lichenoid drug eruptions following different types of vaccination is a possible event. Therefore, the aim of our review is to provide a broad perspective to clinicians by analysing the current literature of cases of LP and lichenoid eruptions following COVID-19 vaccination, and also investigating the possible pathogenetic mechanisms underlying this phenomenon. In total, 61 cases of LP and lichenoid eruption following COVID-19 vaccination have been collected. However, the number of cases of LP and lichenoid drug eruption is extremely low compared with the number of vaccines administered overall, suggesting that the risk of LP and lichenoid eruption following COVID-19 vaccination is extremely low. Certainly, further studies are desirable to identify the population most at risk and the possibility of taking preventive measures.