Abstract
Lichen planus is an inflammatory dermatosis with a prevalence of approximately 1%. Recent meta-analyses show that patients with hepatitis C virus have a 2.5- to 4.5-fold increased risk of developing lichen planus. Lichen planus has also followed vaccinations and has specifically been attributed to the hepatitis B vaccine, the influenza vaccine, and the tetanus-diphtheria-acellular pertussis vaccine. We describe a case of lichen planus in a hepatitis C virus-infected African American male occurring in temporal association with the administration of the tetanus-diphtheria-acellular pertussis vaccine. The patient's presentation was clinically consistent with lichen planus and confirmed by biopsy. It is likely that many cases of vaccine-induced lichen planus have gone unpublished or unrecognized. In areas with high prevalence of hepatitis C virus infection, we may expect to see more cases of vaccine-induced lichen planus especially in light of the updated Centers for Disease Control and Prevention tetanus-diphtheria-acellular pertussis vaccination recommendations. This case serves to educate healthcare providers about vaccine-induced lichen planus and, in particular, the need to counsel hepatitis C virus-infected patients about a potential risk of developing lichen planus following vaccination. We also reflect on current theories suggesting the T-cell-mediated pathogenesis of lichen planus and the role that hepatitis C virus and toxoid or protein vaccines may play in initiating the disease.