There is a hard lump inside the testicle, which is commonly seen in clinical conditions such as epididymitis, orchitis, testicular and epididymal tuberculosis, and testicular tumor. If you find a hard lump inside the testicle, it is recommended to seek medical attention in time to improve physical examination, laboratory examination and imaging examination to clarify the diagnosis and give treatment as soon as possible.1. Epididymitis: Epididymitis is more common clinically, mainly due to the infection of the urethra by pathogenic bacteria such as Escherichia coli and Staphylococcus, and the inflammation invades the epididymis through the vas deferens and causes epididymitis. The inflammation can make the epididymis enlarge, harden, and have a nodular feeling, and there may be a hard lump inside the testicle. It can be accompanied by pain, which may radiate to the groin. In the acute stage, symptoms such as frequent urination, urgent urination, painful urination and fever may occur. The clinical diagnosis can be helped by ultrasound. If it is epididymitis, the patient needs to rest in bed, elevate the scrotum, avoid sexual life and physical labor during the onset. Anti-infection treatment can be given according to the pathogenic bacteria of the infection. Broad-spectrum antibiotics can be used in the acute stage, and symptoms can also be relieved by local hot compresses or sitz baths; 2. Testicular inflammation: mainly caused by the involvement of epididymitis, and can also occur after mumps. In addition to the hard bumps on the testicles caused by inflammation, patients may also experience pain and redness and swelling of the testicles with fever. The treatment is the same as that for epididymitis. If the testicular infection is induced by mumps, antiviral treatment is required. 3. Testicular and epididymal tuberculosis: Testicular and epididymal tuberculosis is often accompanied by the appearance of tuberculosis, secondary to renal tuberculosis. Tuberculosis nodules may appear at the lesion site, and bead-like changes may be palpable. After the inflammation subsides, hard nodules may be left behind, which may appear as a hard lump inside the testicle. Diagnosis can be assisted by ultrasonography. If the diagnosis of testicular and epididymal tuberculosis is confirmed, targeted combined anti-tuberculosis chemotherapy is required. If anti-tuberculosis drug treatment is not effective, surgery is recommended to remove the lesion. 4. Testicular tumor: It is less common clinically and is more likely to occur in young adults, and tumor invasion of the lateral testis can appear as a painless mass, which may appear as a hard lump. Tumor markers, CT, MRI, etc. can help to make a clear diagnosis. If testicular tumor is diagnosed, radical orchiectomy with radiotherapy is usually required.