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Essentials of Diagnosis

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  • • Subacute–acute onset.
  • • Anorexia.
  • • Fever.
  • • Multisystem involvement.

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General Considerations

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The pulmonary vasculitides are a heterogeneous group of systemic disorders (Table 20–1) characterized by vascular inflammation leading to tissue necrosis and subsequent end-organ dysfunction. Pulmonary vasculitis may be a manifestation of an underlying connective tissue disease, such as systemic lupus erythematosus, or may occur in the absence of any other associated, underlying disease, as is the case in microscopic polyangiitis or Goodpasture’s syndrome.

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Table Graphic Jump Location
Table 20–1. Systemic Vasculitides.
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In general, the systemic vasculitides are uncommon and involve the lung with variable frequency. Pulmonary involvement occurs in up to 70–90% of patients with Wegener’s granulomatosis (WG) but is rare in several other disorders such as giant cell arteritis, Behçet’s syndrome, polyarteritis nodosa, cryoglobulinemia, and Kawasaki’s disease. The incidence varies from two to three cases per million people per year for microscopic polyangiitis to 12–13 cases per million people per year for vasculitis associated with the collagen vascular diseases. Recent studies suggest that the incidence of systemic vasculitis is increasing. However, this increase likely reflects the recent availability and widespread use of testing for antineutrophil cytoplasmic antibodies (ANCAs), autoantibodies commonly found in WG, microscopic polyangiitis, polyarteritis nodosa (PAN), and Churg–Strauss syndrome (CSS).

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Vasculitis is defined as inflammation of a vessel involving small, medium, or large arteries or veins. If medium- or large-diameter vessels are involved, infarction, necrosis, and end-organ dysfunction result. In contrast, involvement of small-diameter vessels (ie, capillaries, arterioles, and venules) results in the loss of vascular integrity and leakage of blood into the tissue. Small-diameter vessel involvement in the lung is termed pulmonary or alveolar capillaritis and manifests as diffuse alveolar hemorrhage (DAH). The analogous lesions in the skin and kidney appear as leukocytoclastic vasculitis with visible, raised palpable purpura, and sometimes as petechiae and focal, segmental, necrotizing glomerulonephritis. Although the focus of this chapter is on the pulmonary manifestations of vasculitides, it should be noted that any organ system can be affected.

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Several of the systemic vasculitides can be further subclassified based on their histopathology. WG, CSS, necrotizing sarcoid granulomatosis, giant cell arteritis, and Takayasu’s arteritis all share the similar histological features of granulomatous inflammation.

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Granulomatous inflammation involving small- and medium-diameter blood vessels is characteristic of WG. Concomitant with vascular inflammation and tissue necrosis, a necrotizing granulomatous process is present in the tissue adjacent to and within the wall of the affected blood vessel. An area of central necrosis, surrounded by mixed acute and ...

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