Hypocomplementemic urticarial vasculitis syndrome (HUVS) is a rare, severe form of urticarial vasculitis. It is characterized by persistent hypocomplementemia, chronic urticarial vasculitic lesions, and severe multiorgan involvement. Herein, we present long-term follow-up of two siblings diagnosed with HUVS at early ages, who were found to have DNASE1L3 mutations, and their subsequent 20-year follow-up. While one of the siblings developed lupus nephritis, the other exhibited vasculitic renal involvement. The patients received various treatments, with rituximab proving most effective in the long term. The present study contributes to the existing body of literature on pediatric HUVS, which, to the best of our knowledge, has been described in 28 cases. Renal involvement was present in 82% of patients, and lupus nephritis was most common in patients with renal pathology. Patients received many different treatments. Two patients died, and five patients developed end-stage renal failure. However, it should be noted that follow-up was not conducted in 39% of these patients and the follow-up period was very short for the remaining patients.
