P155 Clinical response to omalizumab in urticarial vasculitis: a case series from an Irish centre

Abstract

Urticarial vasculitis is a rare small-vessel vasculitis characterized by urticarial lesions persisting beyond 24 h with residual purpura or ecchymosis. Management is challenging, and long-term systemic corticosteroids and immunomodulators carry significant morbidity. Omalizumab is licensed for chronic spontaneous urticaria, but evidence for its use in urticarial vasculitis remains limited to case reports and small series. We set out to assess disease control following omalizumab therapy in refractory urticarial vasculitis. We report a retrospective case series of five patients with biopsy-confirmed urticarial vasculitis treated with omalizumab at a tertiary dermatology centre in the West of Ireland. Four patients had normocomplementaemic disease and one had hypocomplementaemic urticarial vasculitis associated with Sjögren syndrome. Omalizumab was initiated at 300 mg subcutaneously every 4 weeks, with dose escalation in one case due to incomplete response. Clinical response was assessed based on lesion persistence, flare frequency, residual purpura and corticosteroid-sparing effect. Disease control was also evaluated using the Urticaria Control Test (UCT) as a patient-reported outcome measure in the absence of validated urticarial vasculitis-specific scoring tools. The median disease duration was > 10 years, with all patients previously refractory to antihistamines and systemic therapies. Four patients with normocomplementaemic urticarial vasculitis achieved complete clinical response, including cessation of new lesions, resolution of postlesional purpura and discontinuation or marked reduction of systemic corticosteroids. The mean UCT improved from 6.6 at baseline to 14.6 following treatment, with all normocomplementaemic cases achieving well-controlled disease (UCT ≥ 12). The single hypocomplementaemic patient demonstrated partial improvement only, with persistent intermittent disease activity and a post-treatment UCT of 10. No serious adverse events were observed. This case series supports omalizumab as an effective and well-tolerated steroid-sparing therapy in refractory urticarial vasculitis, particularly in normocomplementaemic disease.