comparing different small vessel vasculitis

Anti–glomerular basement membrane (GBM) disease (also known as Goodpasture disease) presents with hemoptysis and glomerulonephritis; however, a markedly elevated sedimentation rate is unusual.  Constitutional symptoms (eg, malaise, weight loss, fever, arthralgia) are not typically present, and their presence is more suggestive of vasculitis.  In addition, chest x-ray in anti-GBM disease reveals patchy basilar infiltrates, not the cavitation seen in this patient.

Microscopic polyangiitis (MPA) is another small-vessel vasculitis that commonly affects the lung and kidney. Lung involvement is more likely to present as diffuse alveolar hemorrhage rather than cavitary disease. Typically, MPA is associated with antibodies directed against myeloperoxidase (MPO) that demonstrates perinuclear antineutrophil cytoplasmic antibodies (p-ANCA) immunofluorescent staining. Less commonly, other antigens, such as lactoferrin, elastase, and cathepsin G, will stain in a p-ANCA pattern. MPO p-ANCA staining is associated with a lower risk of relapse, slower decline in kidney function, and a lower mortality rate than PR3 c-ANCA staining.