Lung-dominant connective tissue disease (LD-CTD) is a disease concept for interstitial pneumonia; however, it has not been robustly validated. This study was conducted to elucidate the clinical, radiologic, and histologic features of LD-CTD.
We retrospectively reviewed 44 consecutive patients with serologically defined LD-CTD who underwent surgical lung biopsy. Patients were identified as having LD-CTD if they had specific autoantibodies but did not meet the criteria for connective tissue disease. We conducted a multidisciplinary diagnosis and evaluated major histologic patterns according to the current idiopathic interstitial pneumonias (IIPs) classification of 2013. Characteristic histologic features for LD-CTD (eg, prominent plasmacytic infiltration, lymphoid aggregates with germinal centers), high-resolution CT (HRCT) scan patterns, and prognosis were also assessed.
The major histologic patterns were usual interstitial pneumonia (UIP) in 25 patients and nonspecific interstitial pneumonia (NSIP) in 13 patients. Two or more characteristic histologic features for LD-CTD were observed in 15 patients with histologic UIP (h-UIP) and 11 patients with histologic NSIP (h-NSIP). Fifteen patients with h-UIP (60%) showed an inconsistent UIP pattern on HRCT scan. After multidisciplinary discussion (MDD), 18 patients with h-UIP were labeled as having unclassifiable IIP. The annual change in percent predicted FVC improved significantly in patients with h-NSIP (P = .002), who also had better survival than those with h-UIP (P = .031). In contrast, survival was not associated with HRCT scan pattern (P = .79).
The major histologic patterns in LD-CTD were UIP followed by NSIP. Two-thirds of patients had characteristic histologic features for LD-CTD. A majority of patients with h-UIP were considered to have unclassifiable IIP based on MDD. Patients with h-UIP had worse survival than those with h-NSIP.