ANCA Vasculitides

Learning Objectives:
Overview of ANCA Vasculitis
Wegener's vs MPA
Summary of lab findings

ANCA vasculitides
ANCA diseases are more common among older, white patients, with equal M:F predominance
Symptoms usually consist of malaise, weight loss, fevers, arthralgias/myalgias
Manifestations include sinus, pulmonary and renal disease
Subtypes include Wegener's, Microscopic Polyangiitis, Churg Strauss, renal-limited vasculitis
Churg Strauss is unique in that asthma is the cardinal feature and eosinophilia is common
ANCA vasculitides are small vessel vasculitides, but unlike others do not have immune deposits
All have the potential to cause focal, necrotizing, crescentic pauci-immune GN

The American College of Rheumatology Criteria for WG
    * Nasal or oral inflammation (oral ulcers or purulent or bloody nasal discharge)
    * Abnormal chest radiograph showing nodules, fixed infiltrates, or cavities
    * Abnormal urinary sediment (microscopic hematuria with or without red cell casts)
    * Granulomatous inflammation on biopsy of an artery or perivascular area
When >/= 2/4 present, sensitivity of 88 percent and a specificity of 92 percent
*Note that this criteria may also be met in MPA

Most clinicians distinguish WG from MPA clinically.
Patients with upper respiratory tract inflammation or nodules in the lower respiratory tract with granulomas on biopsy (any organ) are classified as WG
On the other hand, nasal disease and necrotizing vasculitis on biopsy but no evidence of granulomatosis suggests MPA

There are also ANCA-based classifications based on the findings that patients who have proteinase 3 or myeloperoxidase ANCA behave similarly and ANCA subtypes have better predictive value with respect to long-term outcome and relapse propensity than do diagnoses of Wegener’s granulomatosis vs Churg-Strauss syndrome, for example. Regardless of whether our patient has WG or MPA, many of the immunosuppressive agents will be the same.

In general, 80 to 90% of patients with either WG or MPA are ANCA positive
WG is primarily associated with PR3-ANCA
MPA is primarily associated with MPO (myeloperoxidase)-ANCA
10% are ANCA negative

Ref:
The American College of Rheumatology 1990 criteria for the classification of Wegener's granulomatosis
ANCA Small vessel vasculitis. Journal of America Society of Nephrology

(Ellen Eaton MD, 4/11/11)