Scrotal cysts are common, generally non-cancerous masses that develop within the scrotum, the sac of skin holding the testicles. These lumps are typically fluid-filled sacs and are a frequent finding during routine physical examinations. While the discovery of any lump in this area can cause worry, most scrotal cysts are benign and do not pose a serious health threat.
Defining Scrotal Cysts and Their Common Types
A cyst is a closed sac that forms abnormally in body tissue, often containing fluid or semi-solid material. In the scrotum, the two most common types are epididymal cysts and sebaceous cysts. Epididymal cysts, often called spermatoceles, are located within the epididymis, a coiled tube behind the testicle that stores and transports sperm.
Spermatoceles are characterized by the presence of sperm or sperm fragments suspended in fluid, while a simple epididymal cyst contains only fluid. The other common type, a sebaceous cyst, is found on the skin of the scrotum. These cysts are filled with keratin and oily sebum, rather than the fluid associated with the reproductive tract.
Mechanisms Leading to Cyst Formation
The primary cause of epididymal cysts and spermatoceles is the obstruction of the efferent ducts or the epididymal tubule system. When the duct system becomes partially blocked, the continuous flow of fluid and sperm is hindered. This causes a backup and localized swelling that manifests as a cyst.
The precise reason for this blockage is often unknown, classified as idiopathic. However, it can be associated with prior trauma, injury, or inflammation of the epididymis (epididymitis). Exposure to certain potent estrogens, such as diethylstilbestrol (DES) in utero, has also been linked to the development of these cystic structures later in life. These benign masses are generally not caused by sexually transmitted diseases or poor hygiene.
Conversely, a sebaceous cyst forms when the duct of a sebaceous gland on the scrotal skin becomes blocked or damaged. These glands naturally secrete an oily substance called sebum onto the skin surface. When the duct is blocked, the sebum and keratin protein accumulate beneath the skin, forming the characteristic lump.
Diagnosis and Management Options
Identifying a scrotal cyst typically begins with a thorough physical examination. A classic diagnostic technique is transillumination, where a light is shone through the scrotum to determine if the mass is fluid-filled or solid. Fluid-filled structures, like cysts, will allow light to pass through, appearing illuminated, while solid masses, such as tumors, will block the light.
To definitively confirm the diagnosis and rule out more serious conditions like testicular cancer, an ultrasound of the scrotum is the standard imaging procedure. Ultrasound provides a clear image of the internal structure, confirming the fluid-filled nature of the mass and its exact location separate from the testicle.
For the majority of scrotal cysts that are small and cause no pain or discomfort, the standard management is “watchful waiting.” This involves periodic monitoring to ensure the cyst does not change in size or cause symptoms. Intervention is typically reserved for cysts that grow large enough to cause a feeling of heaviness, significant pain, or impact daily activities. In these symptomatic cases, surgical excision, known as spermatocelectomy, is the preferred treatment to remove the entire cyst. Aspiration (draining the fluid with a needle) is rarely performed due to a high risk of the cyst recurring and potential damage to the epididymis.