Why would a nodule/growth seen on CAT scan disappear one month later? Could it have been a cyst?

doctor's thought it was a cancerous growth, perhaps, but now it's gone..

Why would a nodule/growth seen on CAT scan disappear one month later? Could it have been a cyst?
it could have been a inflammatory mass or artifact which disappeared spontaneously.
Reply:Defective!!! Have another,don't take chances!!!