Sebaceous cyst are never life threatening. You can always go and show it to a good surgeon.

Hi.... If a sebaceous cyst does not cause problems or look bad cosmetically, you probably don't need any treatment. If it becomes swollen or tender, home treatments may help. Putting a warm moist compress over the cyst may help it drain, for instance. Resist any temptation to pop or squeeze the cyst, like a pimple. But if it's inflamed and causing discomfort, you should see a doctor.