Ground glass opacities: sign of caution in typical interstitial pneumonia

Typical interstitial pneumonia (IP) is mainly the fibrotic form of interstitial lung disease. In some cases with typical IP, a certain amount of ground-glass opacity (GGO) can be detected on high-resolution computed tomography, however, some important issues, such as the co-existence of GGO and typical IP, still require further investigation by biopsy. After the diagnosis of typical IP, anti-fibrosis treatment is usually considered. Here, we hypothesized that GGO in typical IP could be a manifestation of an acute inflammatory attack requiring immunosuppressive therapy or an indicator of ongoing contact with trigger factors that initiate pathological reactions in typical IP.