A cyst in the epididymis, attached to the testicle, felt as a swelling in the scrotum. The cyst is usually filled with cloudy white fluid, translucent if illuminated. The fluid contains sperm which are largely incapable of life. The condition sometimes occurs in boys, but more usually in men, and causes little discomfort. If it occurs on both testicles, the patient is often rendered sterile. If the cyst becomes excessively large it can be drained after a few months with a needle. In children the cyst can be removed by surgery if necessary.