Ground-glass opacities in lung, what to do?

Process in Evolution: GGO in the lung is usually a process that is evolving and may represent resolving infection but can also represent a neoplasm or tumor in its earliest stages. It must be evaluated and followed very closely with high resolution non-contrast CT scans every 3-6 months, depending on the clinical situation.

Different things: it could be many things- from infection, inflammatory process, edema, malignancy etc.