Cysthttps://en.wikipedia.org/wiki/Cyst
Cyst is a closed sac that may contain air, fluid, or semi‑solid material. A collection of pus is called an abscess, which is not a cyst. Surgical removal of the cyst may be necessary, depending on its type and location.

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  • Ganglion cyst ― Asymptomatic lumps that occur suddenly between joints. If the diagnosis of ganglion cyst is confirmed, the problem may be solved by pressing the nodule hard to burst the cyst inside.
  • Mucocele ― It appears as a soft bump on the lips without any symptoms.