Tonsil cancer is a type of cancer that begins in the cells of your tonsils. Your tonsils are two oval-shaped pads in the back of your mouth that are part of your body's germ-fighting immune system. Tonsil cancer can cause difficulty swallowing and a sensation that something is caught in your throat. Tonsils come in a pair located at the back of your throat in an area known as the oropharynx. Their role is to help fight infection. Tonsil cancer is a type of head and neck cancer. Symptoms often include a painless neck lump and a sore throat. It is a form of oropharyngeal cancer that occurs when the cells that make up the tonsils grow out of control and form lesions or tumors. Treatment for tonsil cancer that hasn't spread beyond the tonsil may include combined radiation therapy and chemotherapy (chemoradiation) or surgery followed by radiation therapy. Advanced tonsil cancers may require a combination of surgery, radiation therapy and chemotherapy. Treatment for tonsil cancer may include radiation therapy, chemotherapy, or surgery. Which approach to care is right for you will depend on a variety of factors. it could be a peritonsillar abscess. A peritonsillar abscess is a bacterial infection which can form a pocket of pus near one of your tonsils. It's often a complication of tonsillitis or mononucleosis. Cysts and abscesses are similar but different.