A 70-year-old patient complains of pain in the lower jaw region on the right. He has been using complete removable dentures for the upper and lower jaw for 12 years. He is smoker. Objectively: the right retromolar region exhibits a 1,5x1,2 cm large proliferation of mucous membrane in form of cauliflower, here and there there are dense fissurelike ulcers. The surrounding mucous membrane is cyanotic, infiltrated. When the teeth are closed, the mentioned formation contacts with the posterior edges of the dentures. What is the provisional diagnosis: