Chapter e40

Diagnosis of the vasculitic syndromes is usually based upon characteristic histologic or arteriographic findings in a patient who has clinically compatible features. The images provided in this atlas highlight some of the characteristic histologic and radiographic findings that may be seen in the vasculitic diseases. These images demonstrate the importance that tissue histology may have in securing the diagnosis of vasculitis, the utility of diagnostic imaging in the vasculitic diseases, and the improvements in the care of vasculitis patients that have resulted from radiologic innovations.

Tissue biopsies represent vital information in many patients with a suspected vasculitic syndrome, not only in confirming the presence of vasculitis and other characteristic histologic features, but also in ruling out other diseases that can have similar clinical presentations. The determination of where biopsies should be performed is based upon the presence of clinical disease in an affected organ, the likelihood of a positive diagnostic yield from data contained in the published literature, and the risk of performing a biopsy in an affected site. Common sites where biopsies may be performed include the lung, kidney, and skin. Other sites such as sural nerve, brain, testicle, and gastrointestinal tissues may also demonstrate features of vasculitis and be appropriate locations for biopsy when clinically affected.

Surgical biopsies of radiographically abnormal pulmonary parenchyma, have a diagnostic yield of 90% in patients with granulomatosis with polyangiitis (Wegener's), and play an important role in ruling out infection or malignancy. The yield of lung biopsies is highly associated with amount of tissue that can be obtained, and transbronchial biopsies, while less invasive, have a yield of only 7%. Lung biopsies also play an important role in microscopic polyangiitis, Churg-Strauss syndrome, and in any vasculitic disease where an immunosuppressed patient has pulmonary disease that is suspected to be an infection.

Kidney biopsy findings of a focal, segmental, crescentic, necrotizing glomerulonephritis with few to no immune complexes (pauci-immune glomerulonephritis) are characteristic in patients with granulomatosis with polyangiitis (Wegener's), microscopic polyangiitis, or Churg-Strauss syndrome, who have active renal disease. These findings not only distinguish these entities from other causes of glomerulonephritis, they can confirm the presence of active glomerulonephritis that requires treatment. Because of this, renal biopsies can also be helpful to guide management decisions in these diseases when an established patient has worsening renal function and an inactive or equivocal urine sediment. Cryoglobulinemic vasculitis and Henoch-Schönlein purpura are other vasculitides where renal involvement may occur and where biopsy may be important in diagnosis or prognosis.

Biopsies of the skin are commonly performed and are well tolerated. As not all purpuric or ulcerative lesions are due to vasculitis, skin biopsy plays an important role to confirm the presence of vasculitis as the cause of the manifestation. Cutaneous vasculitis represents the most common vasculitic feature that affects people and can be seen in a broad spectrum of settings including infections, medications, malignancies, and connective tissue diseases. Because of this, for ...

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