Clinicopathologic correlation of hypocomplementemic and normocomplementemic urticarial vasculitis.

BACKGROUND: Urticarial vasculitis is characterized by persistent urticarial lesions with histologic evidence of leukocytoclastic vasculitis. Hypocomplementemic urticarial vasculitis (HUV) is a distinct clinical entity in a subset of patients with urticarial vasculitis.

OBJECTIVE: We examined presentation of urticarial vasculitis and factors predictive of connective tissue disease.

METHODS: The clinical, histologic, and immunologic characteristics of 132 patients with urticarial vasculitis seen at the Mayo Clinic were examined, and features of the hypocomplementemic patients were compared with those of the normocomplementemic patients.

RESULTS: Twenty-four patients (18%) had hypocomplementemia; all were female. Interstitial dermal neutrophilia was seen in 19 biopsy specimens (83%). On direct immunofluorescence (DIF) testing of lesional skin, 23 patients (96%) had a continuous strong granular deposition of immunoreactants along the basement membrane zone compatible with lupus erythematosus in addition to vascular fluorescence. Systemic lupus erythematosus (SLE) was present or occurred in 13 (54%). One hundred eight patients (82%) had normocomplementemia; 65 (60%) were female. Interstitial dermal neutrophilia was seen in 11 of 26 (42%) randomly selected biopsy specimens. On DIF, one patient (1%) had the lupus band. SLE occurred in three patients (3%).

CONCLUSION: Patients with HUV were more likely to be female, to have diffuse neutrophilia on biopsy specimens stained with hematoxylin and eosin, to have continuous strong granular deposition of immunoreactants along the basement membrane zone on DIF, and to have SLE than normocomplementemic patients. We submit that HUV represents a subset of SLE with shared clinical, laboratory, and immunologic features.