Hydrocele: This condition, characterized by the accumulation of fluid around a testicle, is a common cause of scrotal swelling. It can be primary (idiopathic) or secondary due to trauma, infection, or tumor.

Epididymitis: Inflammation of the epididymis, often due to bacterial infection, can cause scrotal swelling, pain, and tenderness.
Varicocele: An enlargement of the veins within the scrotum, similar to varicose veins, which can cause swelling and a feeling of heaviness.
Spermatocele: A benign cystic accumulation of sperm that arises from the head of the epididymis, which can cause swelling but is usually painless.
Testicular torsion (early stages): Although more commonly associated with acute pain, early stages of testicular torsion can present with swelling before the onset of severe pain.

Testicular Torsion: A medical emergency that requires immediate attention. It involves the twisting of the spermatic cord, cutting off the blood supply to the testicle.
Testicular Cancer: Although less common, testicular cancer can present with a painless testicular mass or swelling. Early detection is crucial for effective treatment.
Fournier's Gangrene: A severe and potentially life-threatening condition involving necrotizing fasciitis of the genitalia, which can start with swelling and pain.

Henoch-Schönlein Purpura (HSP): A form of vasculitis that can cause scrotal swelling among other symptoms like purpura, joint pain, and gastrointestinal issues.
Filariasis: In areas where it is endemic, filariasis can cause scrotal swelling due to the obstruction of lymphatic vessels by filarial parasites.
Scrotal edema in systemic diseases: Certain systemic conditions, such as heart failure, liver cirrhosis, or nephrotic syndrome, can lead to scrotal swelling due to fluid retention or hypoalbuminemia.