Surface microscopy for discriminating between common urticaria and urticarial vasculitis.

Abstract

Urticarial vasculitis is a clinicopathological entity that overlaps with common urticaria, and biopsy is required for differentiation between them. To determine, for the first time, if skin surface microscopy can aid in the clinical differentiation between common urticaria and urticarial vasculitis in daily practice. Lesions in 20 consecutive patients with a clinical diagnosis of urticaria were studied by biopsy and skin surface microscopy (10x dermoscope) after covering the lesions with olive oil. Lesions were photographed with Dermaphot equipment. A biopsy was taken from all patients. Statistical analysis included Fisher's exact test and Cohen kappa statistics (intra-observer reproducibility). Two dermoscopic patterns were observed: (i). a red-lined vascular pattern (17/20 patients); and (ii). a purpuric globular pattern (3/20 patients). Leucocytoclastic vasculitis was demonstrated histologically in all lesions presenting purpuric globules (3/3) but in none of the lesions presenting a dermoscopic red-lined pattern (P < 0.0008). The intra-observer reproducibility for scoring the red lines and purpuric globules was excellent (kappa=0.8). The results of this pilot study suggest that skin surface microscopy, using a 10x dermoscope, detects purpuric globules in urticarial lesions, and that purpuric globules indicate underlying leucocytoclastic vasculitis.