Differential Diagnosis

• Multifocal primary or secondary lung neoplasia
• Multifocal bacterial pneumonia
• Bland or septic emboli
• Pulmonary infarcts
• Pulmonary vasculitis
• Churg-Strauss syndrome
• Necrotizing sarcoid granulomatosis
• Cryptogenic organizing pneumonia

Discussion

Background

Pulmonary vasculitides include several disorders characterized by inflammation of the pulmonary blood vessel walls. Although Wegener granulomatosis is the most common pulmonary vasculitis, Churg-Strauss and necrotizing sarcoid granulomatosis may also affect the lung. The diagnosis requires correlation of clinical presentation and imaging findings with underlying histologic findings and exclusion of more common infectious granulomatous diseases, many of which can exhibit histologic features of vasculitis.

Etiology

• Unknown.

Clinical Findings

Wegener granulomatosis (WG) is a systemic necrotizing vasculitis that commonly affects the lung. The clinical triad of sinusitis, pulmonary disease, and glomerulonephritis characterizes classical Wegener granulomatosis. A limited form of the disease primarily affects the lung.  WG occurs in approximately 3/100,000 people. Affected patients are typically adults in the 4th and 5th decades of life, and men are slightly more commonly affected than women. Early symptoms relate to upper respiratory tract involvement (e.g., rhinitis, sinusitis, and otitis media). Approximately 60-80% of affected patients develop pulmonary involvement with cough, dyspnea, hemoptysis, chest pain and fever. WG may produce tracheobronchial stenosis complicated by stridor, dyspnea, wheezing and hemoptysis. Renal failure is a late complication. C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) may be elevated but are non-specific. A cytoplasmic pattern of antineutrophil cytoplasmic autoantibody (c -ANCA or proteinase 3 ANCA) when confirmed by standard ELISA has a diagnostic specificity of 99%.

Imaging Findings

Chest Radiography

• Unilateral or bilateral, well-defined pulmonary nodules or mass (Fig. A and Fig. B)
• Cavitation (50%); typically thick, irregular walls; may evolve into thin-walled cysts (Fig. G)
• Multi-focal consolidations
• Diffuse bilateral air-space ground-glass opacities and or consolidations
• Tracheal stenosis +/- signs of secondary obstruction or atelectasis
• Rarely lymphadenopathy

MDCT

• Multi-focal irregular pulmonary nodules and or masses; range up to 10 cm diameter (Fig. C-F)
• Cavitation; typically in lesions > 2.0 cm in diameter; thick, irregular walls (Fig. D)
• Nodules / masses tend to be peripheral, juxtapleural; angiocentric in nature (Fig. C-F)
• Juxtapleural wedge-shaped nodules or areas of consolidation (Fig. C-F)
• “Halo” sign of ground-glass opacity surrounding the lung lesions (Fig. C-F)
• Focal or diffuse airway stenosis or endoluminal nodules or masses
• Post-obstructive consolidation
• Post-obstructive atelectasis
• Pleural effusion: < 10% cases

Management

• Combination of various cytotoxic drugs and corticosteroids

Prognosis

• With appropriate therapy, radiologic findings usually improve within a week.
• Larger and cavitated nodules more likely to resolve
• Relapse occurs often
• Good survival: approximately 95% living at 5 years if appropriately treated
• Poor prognosis in patients with pulmonary hemorrhage and or renal failure
• Associated with 2.5-fold increased risk of pulmonary malignancy

Selected Readings

1. Frazier AA, Rosado-de-Christenson ML, Galvin JR, Flemming MV. Pulmonary angiitis and granulomatosis: radiologic-pathologic correlation. RadioGraphics 1998; 18: 687-710.
2. Mayberry JP, Primack SL, Muller NL. Thoracic manifestations of systemic autoimmune diseases: radiographic and high-resolution CT findings. RadioGraphics 2000; 20: 1623-1635.
3. Parker MS, Rosado-de-Christenson ML, Abbott GF. Wegener Granulomatosis. In: Teaching Atlas of Chest Imaging. New York: Thieme, 2006: 611-614.
4. Winer-Muram, HT. Wegener Granulomatosis, Lung. Diagnostic Imaging for Radiology. Salt Lake City: Amirsys, Inc. 2010. Accessed 01/26/10. Last updated 02/20/09