I have discovered a bad rust around the struct tower, any brother can share your ( repair) experience

 

You mean the shock tower? Are you sure its rust and not a disintegrating shock tower bushing? Some pics would help and what vehicle you have (just post it in your signature), different years have different issues.

 

Some earlier model cars in the UK, 98's & 99's are failing MOT tests with similar problems. The area surrounding the shock mount is reinforced with another panel and that's where salt water hides. I've seen them that bad I could push a thumb through the panel so you could see the tire. Imagine hitting a pothole!
If you've still got the other bodyshell maybe cutting and welding those areas. Probably easier to fix the 100 after all.