A small hard lump that can be felt inside the right testicle may be caused by epididymitis, traumatic orchitis, or epididymal seminal cyst. 1. Epididymitis: Epididymitis causes inflammation and enlargement of the epididymis, which can be felt as a lump or hardness when the testicle is touched. 2. Traumatic orchitis: when the testicle is seriously traumatized, it may lead to hematoma or inflammation of the testicle, and there will be obvious lumps when touching the testicle. 3. Epididymal seminal cyst: the epididymis and the vas deferens may form localized cystic changes without pain and itching symptoms, but the epididymis can be touched with a hard surface and locally smooth, and the epididymis and the vas deferens can be found to be connected on examination. Patients who find small hard lumps in the testicles, it is best to first go to the hospital urology department to do a scrotal ultrasound examination, general scrotal ultrasound examination can clarify the specific cause. Through the scrotal ultrasound to check the presence of related lesions.