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Essentials of Diagnosis
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Triad of
Suspect if upper respiratory tract symptoms (eg, nasal congestion, sinusitis) are refractory to usual treatment
Kidney disease often rapidly progressive
Venous thromboembolism commonly occurs
ANCAs (90% of patients), usually directed against proteinase-3 (but may be directed against myeloperoxidase)
Tissue biopsy usually necessary for diagnosis
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General Considerations
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Annual incidence of 12 per million
Occurs most commonly in the fourth and fifth decades of life
Affects men and women with equal frequency
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Usually develops over 4–12 months
Fever, malaise, and weight loss
Upper respiratory tract symptoms develop in 90% of patients
Lower respiratory tract symptoms develop in 60% of patients
Some patients develop both upper and lower respiratory tract symptoms
Upper respiratory tract symptoms can include
Physical examination can be remarkable for congestion, crusting, ulceration, bleeding, and even perforation of the nasal septum
The lung is affected initially in 40% and eventually in 80%, with symptoms including cough, dyspnea, and hemoptysis
Renal involvement (75%) may be subclinical until renal insufficiency is advanced
Other early symptoms can include
Destruction of the nasal cartilage with "saddle nose" deformity occurs late
Patients are at high risk for venous thrombotic events (deep venous thrombosis, pulmonary embolism)
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Differential Diagnosis
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c-ANCA
Caused by antibodies to proteinase-3, a constituent of neutrophil granules
Has a high specificity (> 90%)
In the setting of active disease, the sensitivity of c-ANCA is also reasonably high (= 70%)
p-ANCA
Most patients have anemia, mild leukocytosis, and elevated acute-phase reactants
If kidney involvement is present
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Chest CT is more sensitive than chest radiograph for infiltrates, nodules, masses, and cavities
Pleural effusions are uncommon
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