Very often, a health-care professional can diagnose OHL simply by looking
at the white patch. If there is confusion as to whether the white patch
is OHL or thrush (candidiasis), a simple
scrape test can be performed. Using a tongue depressor or a toothbrush,
the patch can be lightly scraped. If it appears to come off with scraping,
the white patch is probably thrush and not OHL.
To be sure that the white patch is OHL, a health-care provider can send
a sample of the patch to a lab for analysis. The lab will look for the
Epstein-Barr virus (EBV) to confirm a diagnosis of OHL.