Prolonged urticaria with purpura: the spectrum of clinical and histopathologic features in a prospective series of 22 patients exhibiting the clinical features of urticarial vasculitis.

Background: Biopsy specimens of lesions with clinical features of urticarial vasculitis often show a predominantly lymphocytic infiltrate with eosinophils and red blood cell extravasation. Only occasionally is a leukocytoclastic vasculitis encountered, confirming a diagnosis of urticarial vasculitis.

Objective: The aim of this study was to assess the clinical presentation and histologic features of patients who meet the clinical criteria for urticarial vasculitis.

Methods: Patients were recruited who had persistent urticarial lesions individually lasting longer than 24 hours, associated with at least 2 of 3 of the following: pain or tenderness; purpura or dusky changes; and resolution with hyperpigmentation. Patients were interviewed based on a standard questionnaire with regard to their symptoms. Blood tests and chest radiographs were performed to exclude systemic involvement and hypocomplementemia. Skin biopsy specimens were sent for histology and direct immunofluorescence.

Results: Of 22 patients recruited, 19 (86.4%) showed a predominantly lymphocytic infiltrate on histology. Three cases (13.6%) had a neutrophil-predominant infiltrate associated with a leukocytoclastic vasculitis. Twenty (90.9%) had a superficial perivascular infiltrate, and two (9.1%) had a superficial and deep perivascular infiltrate. In all, 21 biopsy specimens (95.5%) showed inflammatory cells within dermal blood vessel walls, obscuring the vessel outline in some. Endothelial cell swelling was seen in 20 biopsy specimens (90.9%), erythrocyte extravasation in 17 (77.3%), nuclear dust in 5 (22.7%), and fibrin extravasation in 2 (9.1%). Multivariate analysis revealed the following features to be independently associated with neutrophil predominance: fulfillment of all 3 minor criteria for urticarial vasculitis-like lesions (P = .007); presence of fibrin on histology (P < .001); presence of nuclear dust on histology (P = .001); hypocomplementemia (P = .001); and anemia (P = .015). There was a trend toward lesions not clearing as readily in the neutrophil-predominant group (P = .071), even with two-modality treatment (P = .089).

Limitations: Serum immunoelectrophoresis was not done to exclude Schnitzler's syndrome. Electronmicroscopy and cytokine profiling were not performed.

Conclusion: Biopsy specimens of lesions with clinical features of urticarial vasculitis reveal that only a minority of patients has leukocytoclastic vasculitis. The majority has a lymphocyte-predominant histology, associated with varying numbers of eosinophils. We favor a lymphocytic vasculitis as a causative explanation in the lymphocyte-predominant group.