What is the percentage of developing the malar "butterfly rash" for lupus patients? i was informed that only 30% will suffer from it.

It depends: Avoid sunlight and you'll probably avoid the butterfly rash. And sun exposure may not even trigger it. Lupus is diagnosed by checklist -- a certain number of checks, with some groups weighted, gives the diagnosis -- and the diagnosis itself is only a guide to "what should we do" for this still-elusive illness. Best of luck. It's an especially challenging disease.

Butterfly rash: Not every patient with lupus have the malar rash, and not every malar rash is lupus. Lupus isn't an easy disease to diagnose, and needs to be managed by specialists, best wishes