A palpable lump with pain in the left testicle may be caused by testicular syringomyelia, varicocele and orchitis. 1. Testicular syringomyelia: Due to various reasons such as orchitis and spermatitis, the secretion and absorption function of the left syringomyelia is out of balance, resulting in excessive secretion of plasma. After the sheath membrane secretes more fluid and forms effusion, the patient will have the feeling of fluid gushing when touching the scrotum, which feels like a testicular mass. 2. Varicocele: when the left side of the varicocele, the left side of the testicle blood circulation is blocked, blood is deposited in the blood vessels, the local temperature of the testicle rises, and the lump can be touched in the left testicle with pain. 3. Orchitis: when the left testicle is infected by bacteria or virus, it will become red, swollen and painful under the influence of germs. In case of abscess, a lump may be felt under the left testicle. There are other causes of left testicular lump with pain, it is recommended that the patient seek medical attention for further examination to clarify the cause and to carry out targeted treatment or therapy.