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Which of the following statements regarding vasculitis is INCORRECT?

A) Vasculitis is defined by clear-cut vascular damage, with or without a cellular inflammatory process.

B) The standardized nomenclature for the vasculitides is based primarily on the size of the involved vessels.

C) Clinically, medium vessel vasculitis results in ulcers, nodules, or reticulated purplish discoloration of the skin.

D) Clinically, small vessel vasculitis results in palpable purpura and petechiae.

E) The histopathologic criteria for recognizing microvascular injury are somewhat arbitrary, and the minimal criteria for vasculitis remain controversial.

The correct answer is A.

Vascular injury can occur in forms limited to the skin. However, in many instances vascular injury occurs in the context of a systemic disease (Table 4-1A). Vascular damage may be the principal event of a disease process, such as in polyarteritis nodosa (PAN); a significant component of a complex disease, as in connective tissue disease or hypercoagulable states; or simply a secondary effect to a localized injury, such as an arthropod bite or traumatic ulcer. Vasculitis is defined as an inflammatory process resulting in clear-cut vascular damage. Histopathologic recognition of vasculitis relies on the recognition of two components: (1) an inflammatory cell infiltrate and (2) evidence of vascular injury. The composition and cellularity of the inflammatory infiltrate of a vasculitis may correlate with the chronology of the process, but not always. Early on, neutrophils and/or eosinophils may predominate. In the late healing stage, the inflammatory cell infiltration may be minimal with an excess of lymphocytes and macrophages.

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Table 4-1A. Definitions of Vascular Injury

Primary Vascular Injury

  • Vasculitis

    • Inflammatory cell infiltrate

    • Clear-cut vascular damage (ie, fibrinoid necrosis of vessel wall)

  • Inflammatory vascular reaction

    • Inflammatory cell infiltrate

    • Limited vascular damage (insufficient for vasculitis)

  • Vasculopathy

    • Lack of inflammation

    • Vascular damage of any degree

Secondary Vascular Injury

  • May present as vasculitis, inflammatory vascular reaction, or vasculopathy

  • Secondary to another insult such as external trauma, ulceration

    • Variable vascular alterations with sparing of some vessels

    • Peripheral perivascular fibrinoid deposition

The histopathologic criteria for recognizing microvascular injury are somewhat arbitrary, and the minimal criteria for vasculitis remain controversial. Various histopathologic features are considered to be indicative of vascular injury. Certain changes, including edema, extravasation of erythrocytes, infiltration of vessel walls by inflammatory cells, leukocytoclasia, and thrombosis, may occur without actual damage to the structural integrity of the vessel. Vessels become leaky for physiologic reasons, leading to edema or even extravasation of erythrocytes and leukocytes. Leukocytoclasia may result from the breakdown of a perivascular neutrophilic infiltrate during the resolution of an inflammatory process unrelated to vasculitis. Similarly, fibrin thrombi may be present in ...

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