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 -
Testicular tumour
Acute epididymitis
Torsion of testis
Acute orchitis
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.