Objective: The purposes of our study were to determine the prevalence of mediastinal lymphadenopathy in idiopathic interstitial pneumonias, correlate their presence with high-resolution CT (HRCT) findings, and assess the potential value of mediastinal lymphadenopathy in the differential diagnosis of idiopathic interstitial pneumonias.
Materials and methods: The study included 206 consecutive patients from three medical centers with pathologically proven idiopathic pulmonary fibrosis (n = 136), non-specific interstitial pneumonia (NSIP) (n = 47), cryptogenic organizing pneumonia (COP) (n = 16), respiratory bronchiolitis-interstitial lung disease (RB-ILD) (n = 5), and desquamative interstitial pneumonia (DIP) (n = 2). HRCT scans were retrospectively reviewed for the presence of mediastinal lymphadenopathy (short-axis diameter, >or= 10 mm), predominant parenchymal pattern, and extent of disease.
Results: Mediastinal lymphadenopathy was seen in 139 (67%) of 206 patients, including 90 (66%) of 136 with idiopathic pulmonary fibrosis, 38 (81%) of 47 with NSIP, six (38%) of 16 with COP, and five (71%) of seven with RB-ILD or DIP. The presence of enlarged nodes was less common in COP than in the other idiopathic interstitial pneumonias (p = 0.04). No significant difference was found in the prevalence of lymphadenopathy in patients with predominant ground-glass opacity (53%) or predominant reticulation (40%). The extent of parenchymal abnormalities was 25-50% in 74 patients (53%), 50-75% in 30 (22%), < 25% in 22 (16%), and > 75% in 13 (9%). A positive correlation between the extent of disease and presence of lymphadenopathy was seen in patients with NSIP (p = 0.01).
Conclusion: Mediastinal lymphadenopathy is a common feature in idiopathic interstitial pneumonias, being slightly less common in COP than in the other idiopathic interstitial pneumonias. The presence of lymphadenopathy therefore has limited value in the differential diagnosis. In patients with idiopathic pulmonary fibrosis, the presence of lymph node enlargement did not correlate to any specific HRCT pattern or to the extent of disease.