In what ways can the lung be involved in SLE?
• Pleuritis (common): should be bilateral. CRP usually elevated (sometimes very high). Consider infection if unilateral presentation and a history of immunosuppression.
• Acute lupus pneumonitis with or without pulmonary hemorrhage (2%): usually seen in a systemically ill patient with diffuse ground glass changes. Bronchoscopy to R/O diffuse alveolar hemorrhage and or infection. Frequently associated with antiphospholipid antibodies.
• Chronic interstitial lung disease/fibrosis: rare in nonoverlap SLE. More common in patients with mixed connective tissue disease or prior acute lupus pneumonitis. R/O medication effects (e.g., nitrofurantoin) or overlap with antisynthetase antibody syndrome.
• Pulmonary hypertension (HTN): R/O secondary causes (chronic emboli and sleep apnea).
• Shrinking lung syndrome: Rare. Decreased lung volumes with normal parenchyma. May be associated with phrenic neuropathy, myopathy of the diaphragm, or pleural fibrosis.
• Cryptogenic organizing pneumonia: Rare. Alveolar disease that is highly responsive to steroids. R/O overlap with antisynthetase antibody syndrome.
• Infection: Typical or atypical. R/O aspiration. Always consider atypical infection with “tree and bud” pattern on CT scan.