title: Vasculitic wheel - an algorithmic approach to cutaneous vasculitides.
abstract: BACKGROUND
  Previous classifications of vasculitides suffer from several defects. First, classifications may follow different principles including clinicopathologic findings, etiology, pathogenesis, prognosis, or therapeutic options. Second, authors fail to distinguish between vasculitis and coagulopathy. Third, vasculitides are systemic diseases. Organ-specific variations make morphologic findings difficult to compare. Fourth, subtle changes are recognized in the skin, but may be asymptomatic in other organs. Our aim was to use the skin and subcutis as a model and the clinicopathologic correlation as the basic process for classification.
  
  
  RESULTS
  We use an algorithmic approach with pattern analysis, which allows for consistent reporting of microscopic findings. We first differentiate between small and medium vessel vasculitis. In the second step, we differentiate the subtypes of small (capillaries versus postcapillary venules) and medium-sized (arterioles/arteries versus veins) vessels. In the final step, we differentiate, according to the predominant cell type, into leukocytoclastic and/or granulomatous vasculitis.
  
  
  CONCLUSIONS
  Starting from leukocytoclastic vasculitis as a central reaction pattern of cutaneous small/medium vessel vasculitides, its relations or variations may be arranged around it like spokes of a wheel around the hub. This may help establish some basic order in this rather complex realm of cutaneous vasculitides, leading to a better understanding in a complicated field.
authors.affiliation: Department of Dermatology and Venereology, Medical University Innsbruck, Innsbruck, Austria.
authors.forename: Gudrun
authors.initials: G
authors.lastname: Ratzinger
authors.affiliation: Institute of Pathology, Medical University Innsbruck, Innsbruck, Austria.
authors.forename: Bettina Gudrun
authors.initials: BG
authors.lastname: Zelger
authors.affiliation: Department of Pathology, Divisions of Dermatology and Dermatopathology, Albany Medical College, Albany, New York.
authors.forename: J Andrew
authors.initials: JA
authors.lastname: Carlson
authors.affiliation: Department of Dermatology and Allergology, Ludwig Maximilian University, Munich, Germany.
authors.forename: Walter
authors.initials: W
authors.lastname: Burgdorf
authors.affiliation: Department of Dermatology and Venereology, Medical University Innsbruck, Innsbruck, Austria.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Zelger
mesh_terms: D000465:Algorithms; D046169:Dermoscopy / Q000379:methods*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008853:Microscopy / Q000379:methods*; D010363:Pattern Recognition, Automated / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D018366:Vasculitis, Leukocytoclastic, Cutaneous / Q000473:pathology*