A hard lump next to the left testicle may be related to epididymitis, epididymal cyst, testicular tumor and other causes. 1. Epididymitis: If inflammatory reaction occurs in the epididymis, enlargement of the epididymis may occur, which may be manifested as a hard lump next to the left testicle. 2. Epididymal cyst: when the cyst is small, the appearance of the scrotum is not big, but the patient may feel a small lump. 3. Testicular tumor: a single painless lump may be palpable in the scrotum of the affected side, or feel dull pain in the scrotum, lower abdominal swelling and discomfort. It is suggested that those who have a hard lump next to the left testicle should go to the hospital in time, clarify the cause of the disease, and carry out standardized treatment under the doctor’s guidance, so as not to bring adverse effects to the body due to the delayed condition.