Several causes. Swelling of the testicles can be caused by infection or by the appearance of cancer. Swelling of the scrotum, which houses the testicles, is much more common. Fluid can build up around the testicle, such as in a hydrocele or spermatocele. Dilated blood vessels called varicoceles can also enlarge the scrotum. If you have this problem, please see your physician or urologist for an examination.
It is rare... To have two swollen testicles, which can be caused by infection of both testes or the appearance of cancer in both of them. It is much more common to have fluid build up around the testicle, swelling up the scrotum on one or both sides and making the actual testicles difficult to feel. If you have this problem, please see your physician or urologist for an examination.
Hydrocele or hernia. Swollen testicles in an infant is most likely from one of two conditions. Most common reason is hydrocele--fluid around the testicles. It could also be from a inguinal hernia. The infant should be seen by a pediatrican to confrim the diagnosis. Also important to make sure it is not painful and no discoloration of skin over it.