What Causes Pink Lunula On Thumb While On Synthroid?

Both the lunulas on the my thumbs are a bright pink color. I have had tests for lupus, CBC and I feel good, no other symptoms. Been to a dermatologist and 2 family doctors they don't know why I have it. I am hypothyroid and take Synthroid, also take Nasonex occastionally but am on no other medications. I also have osteoarthritis