How to treat a sebaceous cyst between your scrotum and anus?

Surgery: If growing or symptomatic then have it surgically removed. It will only grow over time and perhaps become more uncomfortable.

Have it excised: If a sebaceous cyst, it will follow a vicious cycle of filling with sebum, becoming infected, draining, then starting over. If infected now, may require incision and drainage by doctor. Once healed, have sac removed to prevent recurrence. If simple abscess, should not recur once drained.