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.

A cyst is a sac that is filled with a fluid or semi-fluid material. Cysts develop in various places in the body and arise from different parts (tissues) of the body.

An epididymal cyst is a benign (non-cancerous) growth filled with clear liquid which is found at the top end of the testis (testicle) where the spermatic cord (vas deferens) is attached. This area is known as the epididymis.

Cross-section diagram of a testis

Men are most likely to develop these cysts around the age of 40. Children rarely get them before they become teenagers. The number of people who get epididymal cysts is not known.

The first thing you notice is a lump. Epididymal cysts cause no discomfort and you may be unaware that a small one is present unless it gets larger. Some epididymal cysts are found by chance when people have an ultrasound scan (an image of the body using sound waves) for other reasons.

You can get several epididymal cysts on one side of the scrotum or they can occur on both sides. The lump may be small but you are most likely to feel it if it enlarges. It can grow to the same size as the testis. It has a smooth surface and the consistency is described as fluctuant. This means you can squelch it between your fingers like a tiny water-filled balloon as opposed to the hard resistance you feel when squeezing a marble.

The lump can be felt separate from the testis. This is an important feature because cancer of the testis is felt as a knobbly bit on the testis itself and cannot be separated from it.

Because the cyst is filled with fluid, it shines brightly when a light from a torch is passed through it. This is known as transillumination.

  • Spermatocele: this is a cyst which feels like an epididymal cyst but it is filled with semen (sperm).
  • Inflammation: some illnesses cause a thickening of the epididymis and surrounding structures which can feel like an epididymal cyst; however, these swellings do not transilluminate.
  • Hydrocele: this is caused by a collection of fluid in the scrotum.
  • 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'.
  • Lipoma: this is a fatty lump which can sometimes cause difficulty because it can be felt separate from the testis, just like an epidydimal cyst.

Most people do not need any tests. The doctor can make the diagnosis by examining you. If there is any doubt, an ultrasound scan can be arranged. Drainage of the cyst using a needle (aspiration of the fluid) can be performed but this is rarely necessary.

Most men with epididymal cysts are quite healthy.  However, epididymal cysts are sometimes seen as part of another condition:

  • Cystic fibrosis: an inherited illness in which there are cysts in the lungs, pancreas and other areas of the body.
  • Polycystic kidney disease: an inherited condition in which cysts develop in the kidneys and other parts of the body.
  • Von Hippel-Lindau disease: an inherited disease in which tumours develop in the eye, kidneys and nervous system.
  • Epididymal cysts can sometimes occur in children whose mothers have been exposed to a hormone called diethylstilbestrol.
  • If the cyst is small and causing no problems you may need no treatment. You just need to keep an eye on it and seek medical advice if it gets larger or becomes painful.
  • Children rarely need treatment because at this age most epididymal cysts eventually disappear.
  • 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. Names of sclerosants include tetracycline, phenol, sodium tetradecyl sulfate, polidocanol and ethanolamine oleate.

Epididymal cysts rarely cause complications. Very occasionally, a twisting of the cyst on its stalk (a torsion) can occur. This causes sudden pain and swelling on one side of the scrotum. If you experience this it is important to seek medical help fast as urgent surgery is required.

Original Author:
Dr Laurence Knott
Current Version:
Peer Reviewer:
Dr Hayley Willacy
Last Checked:
Document ID:
28454 (v1)
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