Ancillary Staging Techniques

Fiberoptic bronchoscopy with bronchoalveolar lavage (BAL) contributed significant insights into the pathogenesis of IPF and other ILDs but practical value is limited (2,147). Increases in polymorphonuclear leukocytes, mast cells, alveolar macrophages, and myriad cytokines are noted in BAL fluid from patients with IPF lymphocyte numbers are usually normal (147). However, BAL cell profiles in IPF do not predict prognosis or therapeutic responsiveness (147). We do not believe BAL cell counts have a role to stage or follow IPF. 

Historically, gallium citrate (Ga 67) scans were used to assess the extent of intrapulmonary inflammation (alveolitis) in diverse ILDs (15). However, Ga scans are nonspecific, expensive, inconvenient and do not predict prognosis or responsiveness to therapy (2). Thus, Ga scans have no role to stage or follow patients with IPF (15). Clearance of Tc diethylenetriamine pentaacetate (DTPA) aerosol is accelerated in IPF, and is a marker of increased lung permeability (15). Increased metabolic uptake may be noted by positron emission tomographic (PET) scans in patients with IPF (18). However, the sensitivity, specificity and clinical value of DTPA or PET scans to stage or follow IPF have not been elucidated. 

Acute exacerbations of IPF are characterized by rapid development of cough, dyspnea, hypoxemia, and worsening pulmonary infiltrates in patients with known IPF (29,148-151). Presentation is similar to acute respiratory distress syndrome (ARDS) (29,148,149,151,152). The cardinal histological feature is DAD superimposed on a background of UIP (149,151). Idiopathic acute interstitial pneumonia (AIP) (28,152) exhibits similar clinical and histological features as acute exacerbations of IPF, but lacks the requisite features of UIP. High-dose intravenous (IV) pulse methylprednisolone has been used to treat acute exacerbations of IPF, but data on treatment are limited to anecdotal cases and small series (29,148,149,151). This entity is reviewed in chapter 15 and will not be further discussed here. 

Primary bronchogenic carcinoma complicates UIP in 5% to 13% of patients (153-157). The increased risk of lung cancer in IPF may occur in nonsmokers (154), but smoking increases the risk (153,155). Surgical resection is the treatment of choice for patients with localized non-small cell lung cancer (NSCLC) but morbidity and mortality rates are higher in patients with underlying IPF (156,157). 

Pulmonary arterial hypertension (PAH) and right ventricular (RV) dysfunction are common in IPF (158,159). The pathogenesis of PAH in IPF is complex, and does not correlate with Va or extent of pulmonary dysfunction (159-163). Pulmonary artery remodeling and proangiogenic cytokines are likely central to developing PAH in IPF (63,159,160,164), but ablation of pulmonary vessels (165) and vasoconstriction may play contributory roles (159). 

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