MarketplaceHard Lump On Roof Of MouthPosted on February 9, 2010. Hard painless lump in the roof of the mouth and sore throat? Two days ago, I noticed a painless hard lump in the roof of my mouth about 1.5 cm behind the teeth on the hard palate. It is about 5 mm in size. I also have a sore throat that just today. See a dentist asap CommentsThere are no comments.Leave a Comment | Popular My Friends |