The winking eye or winking owl sign refers to the appearances of the spine, when a pedicle is absent - almost always due to a bony metastasis.

The usual appearance of the pedicles representing two eyes on the AP projection is lost, as one pedicle is destroyed - it then appears like one eye is open and the other is winking or shut.

Potential all bony metastases can do this, however breast cancer and lung cancer are the usual culprits.

In this case breast cancer was the primary tumor.