Biloblastic subpleural interstitial lesions are a descriptive term for imaging tests that show signs of interstitial changes in the chest that require prompt medical attention upon detection. Bilobar subpleural mesenchymal lesions are usually just one manifestation of a disease, but they usually have multiple etiologies. The so-called lung mesenchyme usually consists of a combination of connective tissue, nerve fibers, lymphatic vessels, and blood vessels, and a change in one of these components may result in the discovery of mesenchymal lesions on imaging studies. If the connective tissue that makes up the lung interstitium becomes diseased, it is usually due to interstitial pneumonitis or connective tissue disease; interstitial changes can also occur if cancerous lymphadenitis has occurred.