Breaking Out of the Hive: A Case Report on Hypocomplementemic Urticarial Vasculitis Syndrome.

Hypocomplementemic urticarial vasculitis syndrome (HUVS) is a rare autoimmune disorder characterized by chronic urticaria, systemic vasculitis, and hypocomplementemia, posing significant diagnostic challenges due to its overlap with common conditions and varied systemic manifestations. We report the case of a 36-year-old female with a history of post-birth cerebral hemorrhage and seizure disorder, who presented with abdominal pain, diarrhea, and subtle urticarial lesions. Initial investigations by gastroenterology suggested inflammatory bowel disease (IBD), but persistent symptoms and evolving cutaneous signs prompted further evaluation. A skin biopsy demonstrated leukocytoclastic vasculitis, while serological tests showed hypocomplementemia and positive antineutrophil cytoplasmic antibodies (ANCA), confirming HUVS. The patient's management included high-dose corticosteroids and mycophenolate mofetil, with partial symptom relief. Subsequent introduction of rituximab markedly improved her gastrointestinal and dermatological symptoms, highlighting its effectiveness in treating refractory HUVS. This case emphasizes the necessity for vigilance, interdisciplinary collaboration, and personalized treatment adaptations in managing HUVS.