There are hard lumps on one side of the testicle, the possible causes: 1, testicular inflammation, inflammation can be followed by localized swelling, accompanied by hard nodules. As the inflammation heals locally to form scarred fibrous tissue, the texture can become harder. There can be swelling and pain in the acute stage, and there is usually no pain in the chronic stage, but it is easy to recur. Ultrasound examination of the testicles is needed for further identification.2. Epididymal nodules, commonly seen after epididymitis, can appear as focal nodules with a hard texture. When touched by hand in the acute stage, there may be swelling and pain, but there is no feeling in the chronic stage, and ultrasound of epididymis is needed for further identification.3. Testicular tumor, there may be focal sclerosis, and with time, the sclerosis scope may gradually expand, and eventually diffuse to the whole testis, with hardened texture accompanied by increased density. It is necessary to carry out CT examination of testis and testicular tumor index examination to exclude whether there is testicular tumor.