Yes Lupus can go undetected for many years before a person is diagnosed with Lupus.
Some people may have Lupus for many years without even knowing about it and even sometimes if you test negative for the test of Lupus you still may have it.
So if you think you might have Lupus and it still hasn't been detected it could be that it just isn't detectable yet.
My coworker had lupus for around 5 years before it was finally detected even though she went to the doctor for many years before that and had been tested.
Finally 5 years later after living with Lupus she was able to get diagnosed with it and the Lupus eventually got worse and made her unable to continue working.
So now she gets disability payments for the Lupus which took her awhile to get approved for but eventually she did.