The testicles are part of the male reproductive system. They produce sperm and testosterone (male sex hormone). The testicles sit inside a loose sac of skin, known as the scrotum, which hangs down behind the penis.
Testicular lumps and swellings can have many different causes. In rare cases, they can be a sign of testicular cancer. However, most lumps are benign (non-cancerous). Cancer Research UK estimates that less than four in every 100 testicular lumps are testicular cancer.
Types of testicular lumps and swellings
The four main types of testicular lumps and swellings are:
varicocele, a swelling caused by dilated (enlarged) veins within the testicles
hydrocele, a swelling caused by fluid around the testicle
epididymal cyst, a lump caused by a collection of fluid in the epididymis (a long, coiled tube behind the testicles) - if it contains sperm, it is known as a spermatocele
testicular torsion, a sudden painful type of swelling that occurs when a testicle becomes twisted, interrupting the blood supply to the testicles; it is a medical emergency (see below)
See Testicular lumps and swellings - causes for other types of testicular swellings.
How common are testicular lumps and swellings?
Varicoceles are relatively common, affecting about one in seven men. They usually become noticeable after puberty (when the body matures sexually) because by this time the testicles are fully grown and the blood flow to the affected veins increases.
Hydroceles affect 1 or 2 in every 100 newborn male babies. They can also occur in older boys or men after an injury or illness.
Epididymal cysts can develop at any age, but they are most common in middle-aged men and affect up to a third of men.
Testicular torsion usually develops in boys aged 13-17, but it can also occur in men who are in their 20s. It is a rare condition: figures from the US suggest that it affects 1 in every 4,000 males every year.
Any lumps, swellings or changes to the testicles should always be checked by a healthcare professional.
Testicular torsion is a medical emergency and will require urgent surgery within hours of it starting.
Other types of lumps may not require any treatment because they often do not cause any symptoms. Hydroceles in newborn babies often disappear on their own during the first year or two.
If a lump causes pain or discomfort, it may be possible to have it surgically removed. See Testicular lumps and swellings - treatment for more information.