hi, thank you for your query. what you re experiencing is called an epididymal cyst.An epididymal cyst is a fluid-filled sac which grows at the top end of the testicle. It is benign (ie not caused by cancer). Some men get only one; others get several on both testicles. Rarely, they can be associated with illnesses that cause cysts in other parts of the body. Small cysts do not need treatment. Larger ones can be removed or aspirated (drained using a needle) to shrink them, especially if they are painful. other causes can be- 1.Spermatocele: this is a cyst which feels like an epididymal cyst but it is filled with semen (sperm). 2.Hydrocele: this is caused by a collection of fluid in the scrotum. 3.Varicocele: this is like varicose veins of the small veins next to one testis or both testes. It is usually described as feeling like a wriggling bag of worms . Treatment- -Large or painful cysts can be removed surgically. The operation is a simple one and recovery is usually uneventful. Occasionally, infection can set in or you can develop blood clot in the scrotum (a scrotal haematoma). -Sclerotherapy is sometimes used as an alternative to surgery. It involves injecting the cyst with a liquid called a sclerosant. -usually they subside on their own. thank you, wishing you good health