How can i tell if i have testicular cancer or testicular torsion?

Testis cancer: is usually painless and feels like a hard, non-tender lump. Testis torsion is associated with very severe pain of sudden onset & scrum will be swollen & tender. Torsion can be associated with nausea & vomiting. Scrotal ultrasound will demonstrate a tumor, if present. There will be absent testicular blood flow with torsion.