Urticarial Vasculitis Masquerading as Typical Acute Urticaria

ABSTRACT

Introduction: Urticaria is a common condition which has clinical overlap with urticarial vasculitis, a rare entity affecting <1% of the population. We report a case of typical acute urticaria evolving into urticarial vasculitis. Case Description A 58-year-old female with a history of endometrial hyperplasia, Hashimoto's thyroiditis, and asthma was initially seen in Allergy and Immunology clinic following an episode of severe perioperative anaphylaxis, determined to be due to cefazolin. Two months later, she presented with new-onset urticaria and angioedema following a mild self-resolving viral illness. The rash was pruritic, with migratory lesions lasting for <24 hours, and not associated with ecchymoses upon resolution. Initial physical examination was notable for erythematous wheals with blanching. She was started on high dose second-generation antihistamines and received multiple steroid tapers with transient improvement. Four weeks after initiation of the rash, she developed a new-onset burning sensation at its site and subsequently developed painful hyperpigmented purpuric lesions in prior areas of urticaria. She had no associated fever, ocular involvement, abdominal pain, or joint pains. Laboratory values were significant for negative CBC, CMP, ESR, TSH, tryptase, c-KIT mutation analysis, ANA, C1q, C3, C4, and SARS-CoV-2 nucleocapsid antibodies. Extensive autoimmune workup was negative. Skin biopsy revealed leukocytoclastic vasculitis consistent with urticarial vasculitis. Patient was started on omalizumab with initial improvement. Discussion(s) Although initially presenting with acute urticaria, the progression of atypical urticarial symptoms warranted consideration of alternative diagnoses, including urticarial vasculitis. This case highlights the clinical overlap between acute/chronic urticaria and urticarial vasculitis which may result in a delay in diagnosis. Copyright © 2022