Vasculitis (overview) L95.8

Inflammation of blood vessels caused by a characteristic, phased inflammatory process in the walls of various types of blood vessels, which leads to various clinically and/or histopathologically defined clinical and/or histopathological clinical pictures (clinical-pathological entities).

The classification of vasculitides is unsatisfactory because the etiology and pathogenesis of this heterogeneous group of diseases are still poorly understood. In the following, different commonly used classification systems are juxtaposed in a nonprejudicial manner.

Especially in clinical dermatology, historically based, predominantly descriptive diagnostic entities continue to be used, which are not readily reflected in the current classifications, but are of relevant use in everyday clinical practice. The classification that is most appropriate to dermatologic entities is that of Sunderkötter et al:

• Classification by "primary" and "secondary" vasculitis. This classification is not always reproducible, especially since wide areas of overlap exist between the two:
  • Primary vasculitis: Triggering cause remains unknown. Pathogenetically, an immunological "hypersensitivity reaction" underlies. Autoantibodies against neutrophil granulocytes and/or endothelial cells (ANCA/AECA) as well as immunohistological examinations are necessary for clarification.
  • Secondary vasculitis: Vasculitides in the context of underlying diseases (e.g. infections, collagenoses, in rheumatoid arthritis(rheumatoid vasculitis), triggering also possible by numerous drugs).
• Classification according to immunological causes. A distinction is made between:
  • ANCA-associated vasculitis (AAV; granulomatosis with polyangiitis; microscopic polyangiitis; eosinophilic granulomatosis with polyangiitis; special form: drug-induced ANCA-positive vasculitis).
  • Immune complex vasculitis (leukocytoclastic vasculitis)
  • Pauci-immune vasculitis
  • T-cell-mediated granulomatous vasculitis.
• Classification by vessel size and type of inflammation: This classification subdivides vasculitides according to objectifiable histopathologic criteria that take into account, on the one hand, the size of the vessels (small, medium, and large) and the type and composition of the infiltrate (e.g., the significant criterion of leukocytoclasia). "Small vessels" are capillaries, arterioles, and venules; "medium-sized vessels" refers to middle arterial and venous vessels; and"large vessels" refers to the aorta and its direct branches or its branches (e.g., temporal artery). Even with this morphologic classification, there are uncertainties and overlaps, especially when clinical and histologic entities are used synonymously. For example, several clinical entities underlie leukocytoclastic vasculitis (LcV). The common feature of this group is the exclusively histologically detectable pathologic substrate, namely vasculitis with neutrophil leukocyte decay, leukocytoclasia. Thus, even this classification is ultimately unsatisfactory from a clinical point of view.
• Histopathological and immunological classification and assignment of clinical entities (based on Sunderkötter). It has been shown that the occurrence of IgA-containing immune complexes (detection by DIF) has a significant prognostic (rather unfavorable prognosis) and therapeutic significance.
• Cutaneous small vessel vasculitis [CSVV]:
  • LcV, largely IgA-associated:
    • Schönlein-Henoch purpura
    • Infantile acute hemorrhagic edema (age < 2 years).
  • LcV (non-IgA-associated)
    • LcV (non-IgA-associated) - with/without systemic involvement.
    • Urticariavasculitis:
      • Normocomplementemic urticarial vasculitis.
      • Hypocomplementemic urticarial vasculitis.
    • Serum sickness
    • Vasculitis associated with essential cryoglobulinemia.
  • Other (special forms):
    • Granuloma (eosinophilicum) faciei
    • Erythema elevatum diutinum
    • Septic vasculitis
    • Purpura fulminans
    • LcV with eosinophilia (entity questionable)
    • LcV in collagenoses (SLE, scleroderma).
• Vasculitis of medium-sized vessels:
  • Systemic (ANCA-positive) vasculitides:
    • Granulomatosis with polyangiitis (Wegener's granulomatosis).
    • Eosinophilic granulomatosis with polyangiitis (Churg-Strauss syndrome)
  • Polyarteritis nodosa (PAN) group:
    • Polyarteritis nodosa, systemic
    • Microscopic polyangiitis (polyarteritis nodosa microscopic)
    • Polyarteritis nodosa, cutaneous
  • Other:
    • Nodular vasculitis (erythema induratum).
    • Kawasaki syndrome.
• Large vessel vasculitis:
  • Arteritis temporalis
  • Takayasu arteritis

The histological classification of a vasculitic process is performed in 3 steps (Ratzinger et al. 2015):

• 1. overview magnification: differentiation between small and medium-sized vessels
• 2. medium magnification: definition of the vessels affected - capillaries vs. post-capillary venules, arteries vs. veins - .
• 3. high magnification: definition of the cell infiltrate (leukocytoclastic, granulomatous, other infiltrate). Note: Vasculitis is always accompanied by an infiltrate in the vascular wall.

Trigger of secondary vasculitides

Clinical classification of primary vasculitides (Chapel Hill Consensus Conference)

Therapeutic strategies for vasculitis (after Fiorentino)

Algorithm for diagnostic clarification in vasculitis (modified according to Fiorentino)

Phlebitides as vascular wall inflammations of larger trunk and extremity veins are also "vasculitides". However, they do not belong to the vasculitides listed here in the narrower sense. This also applies to endangiitis obliterans, which, as an independent vasculitic clinical picture with obligatory occlusive symptoms, is rather classified as an arterial occlusive disease. In many classifications, the term " vasculopathy" is also used, a general term for primarily non-inflammatory vascular diseases associated with partial or complete occlusion of a vessel (e.g., livedo racemosa). Because vasculitides of the skin organ are often associated with focal hemorrhage, the descriptive term "purpura" (e.g., Schönlein-Henoch purpura, anaphylactoid purpura, et al.) has been used in previous literature as a clinical diagnosis for an underlying "hemorrhagic leukocytoclastic vasculitis." The term"purpura" contains a vagueness dictated by history that we will not correct here.

1. Baigrie D et al (2022) Leukocytoclastic vasculitis. 2022 Aug 8. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing PMID: 29489227.
2. Chen KR et al (2002) Clinical and histopathological spectrum of cutaneous vasculitis in rheumatoid arthritis. Br J Dermatol 147: 905-913.
3. Crowson AN et al (2003) Cutaneous vasculitis: a review. J Cutan Pathol 30: 161-173.
4. Fiorentino DF (2003) Cutaneous vasculitis. J Am Acad Dermatol 48: 311-340.
5. Gibson LE (2001) Cutaneous vasculitis update. Dermatol Clin 19: 603-615
6. Makol A et al (2015) Rheumatoid vasculitis: an update. Curr Opin Rheumatol 27:63-70.
7. Muller CSL et al (2016) Diagnosis and histologic features of cutaneous vasculitides/vasculopathies. Act Dermatol 42: 286-301
8. Sundkötter et al (2004) Leukocytoclastic vasculitis. Dermatol 55: 759-783
9. Wiik A (2005) Clinical and laboratory characteristics of drug-induced vasculitic syndromes. Arthritis Res Ther 7: 191-192.