Hello Dear Thanks for your query. I will be most happy if I could help you out. By going through your query one thing which I noticed is that you are very well versed with medical terms. First of all I would like to tell you that not every swelling is cyst or cancerous. Usually these swellings are as result of more common causes, so keep calm and be relaxed. Now the swelling which you have noticed may be any swollen gland or it may also be any other inflammed normal structure. This inlammation may result from any type of infection or it may be due to impinging of the retainer on soft tissue of the oral cavity. • So I will advice you to get an appointment with your dentist so that he/she will rule out the exact cause of your problem and provide the needful treatment. Hope this will help you. If there is any more query or question regarding this in your mind, you are free to ask me any time. Take Care