The testes can swell for many reasons including cancer, testicular torsion, inguinal hernia, epididymitis, hydrocele, and varicocele. Other causes are far less common in adults. Like it or not, your husband needs to see a doctor to get a diagnosis. The first test will be a medical history and an examination. He will not be cut! Treatment will depend upon diagnosis, which many take additional tests like ultrasound scan or blood tests before doctors even know what it is. Sometimes, fear of the unknown keeps us from knowing...but urge him to seek medical help and let us know how it goes!