There are more causes of hard lump in right testicle, and the common causes are testicular cancer, testicular inflammation and syringomyelia. 1. Testicular cancer: it is a rare testicular malignant tumor, the cause of which is still unclear or related to cryptorchidism. The main symptom is single painless swelling in testis. If this disease occurs in the right testicle, with the development of the disease, there will be obvious hard lumps, may also be accompanied by testicular swelling, dull pain and other abnormalities. 2. Testiculitis: this disease can be caused by sexual contact, urinary system diseases, mumps, testicular-epidymal tuberculosis and other reasons, after the onset of testicular contents will be rapidly enlarged, and some patients may have hard lumps in the right testicle, tenderness and other abnormalities. 3. Syringomyelia: this disease is mainly caused by the formation of a large amount of fluid accumulation in the testicular sheath membrane cavity, most of the patients do not have conscious symptoms, but there are individual patients with the increase of fluid accumulation, one side of the testicle will appear ovoid or pear-shaped lumps, and there is no obvious pressure and pain sensation. There may be other reasons for a hard lump in the right testicle, after finding a hard lump in the right testicle, it is necessary to go to a regular hospital in time for examination and actively cooperate with the doctor for treatment, so as not to delay the condition.