A small lump on top of the testicle can be caused by scrotal skin diseases such as folliculitis and other diseases such as tuberculosis of the epididymis, epididymal cysts, orchitis, and testicular tumors. 1. Folliculitis: If the local skin of the scrotum is not cleaned in time, it may form hard boils on the surface of the scrotal skin. 2. Epididymitis, epididymal tuberculosis, epididymal cyst: when there is epididymitis, epididymal tuberculosis or epididymal cyst, multiple inflammatory nodules or tuberculous nodules may form on the surface of the epididymis, and hard bumps on the surface of the testicles may be found on palpation. 3. Testicular inflammation: if the previous testicular inflammation, testicular tuberculosis and so on are not treated in time, or the treatment is not complete, the nodules may be left behind. 4. Testicular tumor: when there are painless bumps, you also need to be alert to the possibility of testicular tumors, etc., and you can perform ultrasound for further examination. Therefore, when you find small bumps on top of the testicles, it is recommended to go to the hospital to clarify the cause of the disease, and further treatment under the guidance of the doctor.