White patch on tongue

I've diagnosed with genital warts.  My husband has no symptoms.  I've read many postings from this site that oral warts are rare.  My concern is that my husband has developed this white patch on his tongue towards the back of his tongue.  I see pin size little while bump on it.  The patch is about a size of a dime.  We've been to our dentist and family doctors, but they weren't sure what it is.  One thought it was a thrush.  It's been going on for a year.  No pain whatsoever.  No lesions.  Recently my husband has been diagnosed with gallstones.  Should we ask our family doctor to do a biopsy on the patch?  If we want to see a specialist, should we go see a dermatologist or ENT?