Boys and men will sometimes experience pain, swelling, or unusual growths in and around the testes. Some of the conditions that can cause such lumps, swelling, and/or pain include torsion (twisting) of the testicle; injury or infection; a hydrocele, varicocele or spermatocele; an inguinal hernia; and kidney stones.
There are also tumors that grow in the testicles that are not always cancerous (malignant). These include stromal tumors, rare types of testicular tumors that occur during childhood. This type includes Leydig cell tumors and Sertoli cell tumors.
However, a medical professional should be seen for any of these symptoms: a painless lump or swelling in either testicle, pain or discomfort in a testicle or the scrotum, changes in the way a testicle feels, a feeling of heaviness in the scrotum, a dull ache in the lower abdomen or groin, a sudden buildup of fluid in the scrotum, or breast tenderness or growth
The occurrence of testicular cancer is estimated to be about 1 in 200, with about 80,000 cases each year in the U.S. It is the most common cancer in American males between the ages of 15 and 35, but also has a 95% survival rate.