Normocomplementemic Urticarial Vasculitis Following Influenza Vaccination: A Case Report and Review of the Literature.

Urticarial vasculitis is characterized by persistent urticarial lesions lasting over 24 h. Urticarial vasculitis is often triggered by medications, infections, and autoimmune disorders. However, vaccinations against viral and bacterial pathogens have recently been documented to induce urticarial vasculitis. We describe the case of a 67-year-old woman who was presented with an extensive erythematous and purpuric rash without systemic symptoms 3 days after an influenza vaccination. She was diagnosed with normocomplementemic urticarial vasculitis based on clinical findings, normal complement levels, and histopathological findings of leukocytoclastic vasculitis. After receiving oral histamines, she showed complete resolution 3 months after receiving the influenza vaccination. Although vaccination-associated vasculitis is common, urticarial vasculitis following vaccinations is rare. We reviewed 13 cases of urticarial vasculitis following a wide range of vaccines, including those against Bacillus Calmette-Guérin, serogroup B meningococcus, influenza, and coronavirus disease. We conducted a comprehensive review of various aspects, including age, sex, past medical history, type of vaccination, number of vaccinations, onset time, cutaneous symptoms, place of eruption, systemic symptoms, laboratory disorders, treatment period, and treatment of urticarial vasculitis. Two patients developed hypocomplementemic urticarial vasculitis after vaccination, and both experienced systemic symptoms such as arthralgia and fever. In this review, no significant differences were found in the data, which may be attributed to the small number of cases. The mechanisms underlying the induction of urticarial vasculitis by vaccines remain unknown; however, in addition to immune complex deposition and complement activation due to vaccine components, molecular mimicry may trigger urticarial vasculitis by producing vaccine-derived pathogenic antigen antibodies. This case study emphasizes the need for heightened awareness and further investigation of urticarial vasculitis as a rare adverse effect of vaccination.