If a hard nodule is palpable on the testicle, an ultrasound examination of the scrotum, such as the testicle, is needed to further define the possible cause.1. If there has been a history of testicular inflammation, a hard nodule may appear as a result of localized fibrous connective tissue hyperplasia or scarring nodule-like changes that may have occurred during the healing process of the inflammation. Acute phase may have pain, chronic phase usually no obvious pain. It is only a hard nodule that can be touched with the hand. This condition generally does not require any treatment and does not cause any functional disorders in patients.2. If there is a history of epididymitis, chronic epididymal nodules can be formed during the healing process, which may cause intermittent chronic pain or painlessness, and ultrasound examination of the epididymis is needed for further identification.3. If there is a testicular syringomyelia or testicular trauma, localized keloid nodule-like changes may occur, requiring scrotal examination, as in the case of scrotum, and then a testicular examination is needed. If there is testicular syringomyelia or testicular trauma, there may be localized scarring and sclerosis-like changes, and ultrasound of the scrotum, such as the testicles, is needed for further identification.