Who told you it was a cyst? A cyst is an epithelial lined cavity. That’s it. Needs to be biopsied and should be sent to an oral and maxillofacial pathologist for diagnosis.

That depends where the cyst is located. Most likely cysts filled with mucous on the lower lip become encapsulated and need to be surgically removed and repaired while avoiding a cosmetic deformity. These Cysts are typically caused by patients injuring or biting their lower lip

YES! This must be removed and sent for a biopsy. If it is not removed it may continue to enlarge and potentially damage the jaw or the teeth. While true cysts are generally benign, and once removed do not "grow back" some can actually be tumors or have a tendency to re occur. Only a biopsy will detect these things.

Dr. Spiro Karras

Most typically yes. Could be numerous types of bad disease that could get worse if left alone. Should at least be looked at by someone qualified, like a board certified oral/Maxillofacial surgeon

Most likely it will need removal. Best to get it looked at by an oral surgeon; some "cysts" can be very aggressive!