40-year-old men are suffering from fever & pain in the scrotum which is not relieved by elevation of the testis. 3 days before had sexual contact with a young female -
Torsion of testis can be differentiated from acute epididymitis by Prehn's sign. ie

On the elevation of testis the pain increases in → Torsion
On the elevation of the testis, the pain decreases in → epididymoorchitis.
Don’t be confused with fever, it can also occur in torsion, especially in older patients.
Testicular tumour
Acute epididymitis
Torsion of testis
Acute orchitis