Will lytic lesions light up on bone scan? doesn't it just show osteoblastic activity, not -clastic? or do osteoclastic maybe show up as "cold spots"?

Smart question: I wondered about that myself. It could be the balance between blastic (forming) and clastic (dissolving) bone which determines the lighting process. Usually, lytic are cold and do not light up. Blastic lesions do. Thanks.

It's complicated...: Purely lytic lesions which can be seen in diseases such as multiple myeloma may not show up on tc bone scan and these lesions may be cold on bone scan. However, lesions can be mixed (with lytic and blastic components) and these often show up on bone scan. Lastly, sometimes there is a blastic response to a lytic lesion...This can also show up on bone scan.

osteoclastic - cold: Lytic lesions can be cold(photogenic) on bone scan if host bone does not react or tumor growing too fast to allow host response with reparative bone. Some times bone infection will be under pressure and not allow blood to to deliver isotope to area and it will be cold..Osteoblastic or repair activity usually shows as increased uptake.Myeloma can induce osteoclastic activity, cold lesions in bone.