There are more reasons why testicles are swollen with hard nodules but not painful, which may be caused by orchitis, epididymitis, syringomyelia and testicular tumor. 1. Orchitis: mostly caused by germs infection, patients may or may not have pain, when there is pus, there will be swelling with fluctuating sensation. 2. Epididymitis: mostly caused by bacterial infection, the patient may have bacterial prostatitis, the treatment is not complete, leading to the spread of bacterial infection caused by epididymitis, the majority of patients will have pain in the scrotum, but some patients will not have pain symptoms. 3. Syringomyelia: mainly caused by abdominal fluid flowing into the syringomyelia cavity through the unclosed syringomyelia tube, the patient’s scrotum and groin will appear lumps, usually without pain. 4. Testicular tumor: initially, patients may not have obvious symptoms, there may be hard lumps in the local area, along with the swelling of lymph nodes in the inguinal area and other phenomena. It is recommended that patients go to the hospital in time for a comprehensive examination, get an accurate diagnosis with the help of doctors, and then give effective treatment.