What causes ground-glass nodules in the lungs?

Ground-glass nodules detected by imaging examinations in the lungs may be caused by pulmonary inflammation, old pulmonary lesions, or lung tumors.

1. Pulmonary Inflammation

Infections such as viral, bacterial, tuberculosis, or Aspergillus infections may lead to localized lung lesions, appearing as focal nodular shadows on imaging.

2. Old Pulmonary Lesions

Scarring left over from previous lung diseases may present as localized lesions, sometimes appearing as nodules. When the density is relatively low, these scars may appear as ground-glass nodules.

3. Lung Tumors

In early stages, lung tumors may appear as ground-glass opacities with relatively low density and indistinct borders. Some patients may show spiculated margins, suggesting malignancy. To determine whether a lung nodule is benign, in addition to evaluating its imaging characteristics, dynamic observation of changes over time is essential—such as repeating lung imaging after three months. If the nodule disappears following anti-inflammatory treatment, it likely represents an inflammatory origin. If the nodule remains stable over time, it may indicate an old lesion; even if it is a tumor, it could be a low-grade malignancy. However, if the nodule shows significant growth, fails to respond to anti-inflammatory therapy, or enlarges rapidly within a short period, this raises suspicion for a lung tumor.

In addition, assessment can be supported by tumor marker tests and lung cancer antibody testing, along with consideration of medical history, smoking history, and family history.