Page 277 - The Vasculitides, Volume 1: General Considerations and Systemic Vasculitis

Systemic Vasculitis and the Lung 251

Small Vessel Vasculitides

Parenchymal and airway disease occur more commonly in SVV than MVV and LVV.
Alveolar hemorrhage is the hallmark of GPA, MPA and EGPA; bronchial stenosis is more
characteristic of GPA, and asthma is most consistent with EGPA.

Granulomatosis with Polyangiitis

Overall, 70% to 100% of patients with GPA show lung involvement, with clinical
manifestations ranging from mild cough, dyspnea, chest pain, and intermittent hemoptysis to
acute respiratory distress syndrome and massive alveolar hemorrhage. In 6% of patients, lung
involvement remains asymptomatic, especially with lung nodules. Lung nodules are among
the most characteristic signs, present in 40% to 66% of patients with GPA, occurring as ? 10
unilateral, bilateral, single or multiple lesions, with a wide differential diagnosis, including
primary and metastatic tumors, tuberculosis and fungal infections (Table 2). Alveolar
hemorrhage, noted in 8% to 30% of patients with GPA, can occur at symptom onset or later
in the disease course and are associated with lung nodules. In all, 30% to 50% of patients
show other pulmonary infiltrates or lung consolidations, and 9% to 28% show pleural
effusion. Spontaneous pneumothorax and pyopneumopthorax can occur, sometimes related to
nodule cavitation and rupture. Pulmonary embolism may be a clue to the presence of active
GPA. All patients should undergo chest CT, because small nodules, alveolar hemorrhage and
other early lesions may be missed by chest radiography at disease onset. Even when the
diagnosis of GPA is clinically apparent, bronchioalveolar lavage should be considered to
exclude concurrent infection and clinically silent alveolar hemorrhage. Surgical lung biopsies,
targeting nodules and consolidated lesions, have a diagnostic yield of up to 91%.

Microscopic Polyangiitis

Alveolar hemorrhage and pulmonary–renal syndrome can be observed in MPA
[57, 66, 67]. Bronchial arteritis with intimal thickening and focal destruction of the internal
elastic lamina and subintimal fibrous scarring of the media are typical histological features in
diagnostic tissue biopsy specimens. Diffuse alveolar damage and pulmonary fibrosis
(Figure 6) can complicate MPA, mainly in patients with anti-MPO P-ANCA MPA. Of note,
pulmonary fibrosis and vasculitis may have independent outcomes, with progression of the
fibrosis despite sustained good control of the vasculitis [25, 28].

Eosinophilic Granulomatosis with Polyangiitis

This rare pulmonary and systemic SVV with an annual incidence of 0.5 to 6.8 per million
and a prevalence of 10.7 to 14 per million, develops through three prototypical successive
phases. The prodromal phase begins with asthma and allergic manifestations, followed by
tissue eosinophilia affecting visceral organs such as the lung and myocardium, and later

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