Italian? very likely.
DeRosa? very unlikely.
All I can say for sure is the headlugs and other (visible) framebits look fairly common and fairly generic, the brake bridge MIGHT be a GPM and the dropouts MIGHT be Shimano (Yes, Italians sometimes used them), but hard to ID with the pics displayed. Edit: on second look I think more likely GPM or some similar Italian brand forged DO, don't think they're Shimano now.
One thing that's distinctive is that forkcrown which is the same as on my early '90s Ciocc, which this frame is NOT...still have not ID'd what brand this Italian crown is, either but the forkblades were Columbus.
Also unless there are matching serial numbers that fork may not be OEM to the frame: the domed stay ends are not a style match to the forkend brazing, for example.