Epididymitis: This is an inflammation of the epididymis, usually caused by a bacterial infection. It's a common cause of scrotal swelling, especially in young men, and is often associated with symptoms like pain, redness, and warmth of the scrotum.

Hydrocele: A condition characterized by the accumulation of fluid around a testicle, leading to scrotal swelling. It can be primary (idiopathic) or secondary due to other conditions like injury or infection.
Varicocele: An enlargement of the veins within the scrotum, similar to varicose veins. It's more common on the left side and can cause a feeling of heaviness or aching in the scrotum.
Orchitis: Inflammation of one or both testicles, usually caused by bacterial or viral infections. It can present with scrotal swelling, pain, and may be accompanied by epididymitis.

Testicular Torsion: A medical emergency where the spermatic cord becomes twisted, cutting off the blood supply to the testicle. It requires immediate attention to save the testicle and is characterized by sudden, severe pain and swelling.
Testicular Cancer: Although less common, testicular cancer can present with scrotal swelling, a testicular mass, or pain. Early detection is crucial for effective treatment.
Fournier's Gangrene: A rare but serious condition involving necrotizing fasciitis of the genitalia, which can start with swelling and pain of the scrotum. It's a medical emergency requiring prompt surgical intervention.

Spermatocele: A cystic structure that forms at the head of the epididymis and contains sperm, which can cause swelling but is usually painless.
Scrotal Hematoma: Bleeding into the scrotum, which can occur after trauma and may present with swelling and pain.
Filariasis: In areas where it's endemic, filariasis can cause scrotal swelling due to the parasitic infection affecting the lymphatic system.