Which connective tissue disease-associated ILD is considered a restrictive lung disease?

The choice identifying interstitial lung disease (ILD) as a restrictive lung disease is correct because ILDs primarily affect the interstitium or framework of the lung, leading to a loss of lung compliance. This results in a reduction in the total lung capacity, which is the hallmark of restrictive lung diseases. In these conditions, the ability of the lungs to expand during inhalation is compromised, causing patients to experience difficulty in taking a full breath.

Interstitial lung disease can be associated with various connective tissue diseases, including rheumatoid arthritis, systemic sclerosis, and lupus. The inflammatory and fibrotic processes that characterize these diseases lead to scarring of lung tissue, further limiting lung expansion and function.

The other options presented do not align with the characteristics of restrictive lung disease. Cystic fibrosis primarily causes obstructive lung disease due to mucus buildup, leading to airway blockage. Bronchiectasis, while it can coexist with restrictive features, is predominantly an obstructive condition characterized by permanent dilation of bronchi due to infection and inflammation, resulting in impaired airflow. Asthma is also an obstructive airway disease, marked by bronchoconstriction and inflammation, not restriction of lung volume. Therefore, interstitial lung disease stands out as the correct association with restrictive lung pathology.