Main symptom are eyes and nose. Would lip biopsy even find anything?

HI guys, I already had a blood test and nothing was found. I don't struggle with dryness in my mouth (or very little) so I'm afraid the lip biopsy won't even find any inflammation. Mostly my eyes and my nose (sinus) very dry. I don't want to do the biopsy if there's a risk that it also won't diagnose me :(