Lytic lesions

My mother (72 Yrs) was made to undergo CT scan of the skull when she had a complaint of persistent and recurring pain in the eye brow region.  In the scan report, it was reported "multiple lytic lesions seen in the skull vault (bilateral Sphenoid wing)".  Further Bone scintigraphy to rule out metastasis has been suggested.  What are multiple lytic lesions and what is bone scintigraphy?  Is the latter really needed?  Can more light be thrown on this?

[Dr Vinod]

Lytic lesions are seen in a scan as a sign of Metastasis.
They suggest that the cancer has spread(Metastasis) to the brain and it is a bad sign clinically.
Sphenoid is a skull bone and the cancer has spread here.
Only by seeing lytic lesions the clinician does not want to come to conclusion and want to do a confirmatory test in Bone Scintigraphy!