Author: Dr Selene (Shau Ying) Ting, Dermatology Registrar (2023)
Reviewing dermatologist: Dr Ian Coulson (2023)
Edited by the DermNet content department
A 65-year-old man presented with a one week history of a widespread, itchy, painful rash affecting various parts of his body. The itchy weals progressed and expanded over a few hours and were persistent, lasting 48 hrs, painful, and resulted in some bruising.
He has a history of hypertension for which he took candesartan. He also had a total hip joint replacement one month prior to the onset of the rash, for which he was taking aspirin as VTE prophylaxis.
On review, he was febrile at 38.1°C and shivering with chills. His pruritus score was 9/10 and his pain score was 6/10. The rash was polymorphous.
His blood tests revealed a CRP of 91, with a normal white cell count.
Biopsy showed fibrinoid necrosis of small upper dermal vessels and leukocytoclasis.
There are annular, indurated, urticated plaques, with petechiae and purpura centrally in some areas. There are also targetoid lesions.
Given the morphology and history of the rash, the differential diagnoses included:
With the histology showing leukocytoclastic vasculitis in specimen one (arm), the likely diagnosis is urticarial vasculitis. Weals lasting more than 24 hrs, bruising, and pain with itch are typical clinical findings.
Treatment is based on the systemic effects and the extent of cutaneous involvement.
As this patient was very symptomatic, he was started on a weaning course of prednisone and antihistamines (cetirizine 20 mg twice daily).
Other potential treatment options for urticarial vasculitis include dapsone, colchicine, hydroxychloroquine, or immunosuppressive medications such as ciclosporin or azathioprine.
Consideration should be given to possible underlying causes such as SLE, Sjogren syndrome, gammopathies, leukaemia, internal cancers, hepatitis B and the use of some drugs, although many cases are idiopathic.
