Endothelial cell pathology as a marker for urticarial vasculitis: a light microscopic study.

Various criteria have been used for the diagnosis of urticarial vasculitis, and for the classification of patients with chronic urticaria. In the present study, semithin Epon-embedded sections were obtained from fifteen patients using a method of fixation optimal for the preservation and examination of the dermal microvasculature. This allowed patients to be classified according to the presence or absence of significant endothelial cell pathology. This feature proved a more reliable indicator of associated humoral abnormalities than the nature of the perivascular infiltrate as seen on paraffin-embedded sections. Endothelial cell necrosis per se was a rare event and could not be used as a reliable criterion for the diagnosis of urticarial vasculitis. Most cases showed either endothelial hypertrophy or shrinkage.